[258]TreviranusArachnid.7—.t.l.f.1.r. f.10. Comp.N. Dict. d'Hist. Nat.xxx. 419. Latreille calls these gillsPneumo-branches.[259]TreviranusIbid.24.PlateXXIX.Fig.1.[260]PlateXXI.Fig.3.a b.[261]Ibid.a.[262]Ibid.b.[263]SprengelCommentar.t.i.f.1.[264]Ibid.f.10.[265]Ibid.t.ii.f.15.[266]Malpigh.De Bombyc.t.iii.f.3.[267]Ibid.t.iv.f.1.[268]LyonetAnat.101.[269]LyonetAnat.101.[270]Sprengel (ubi. supr.16.) says that he never found more thantwo; but as Lyonet affirms that he has very often separated them (102), his accuracy cannot be questioned.[271]LyonetAnat.103.[272]Ibid.Cuv.Anat. Comp.iv. 438. This author says that theintermediatetunic is the spiral thread (437).[273]Lyonet 102.[274]Ibid. 104. SprengelCommentar.17.[275]Lyonet 104. SprengelCommentar.17.[276]Lyonet 102. Malpigh.De Bombyc.12. Reaum. i. 130.[277]Swamm.Bibl. Nat.t.ii.f.7.[278]Lyonet 411.[279]Professor Kidd (Philos. Trans.1825. 235.) conjectures that the tracheæ, as well as air-vessels, may possibly be blood-vessels; but this hypothesis is inconsistent with the fact recently discovered by Dr. Carus, of a circulation, by other means, in larvæ. See CarusIntrod. to Comp. Anat.&c. ii. 400.[280]N. Dict. d'Hist. Nat.xvii. 541. Reaum. vi. 397.PlateXXIX.Fig.8. showsthreeof them ata.[281]Essay on the Bots, &c.23.t.i.f.7, 32, &c.[282]Ibid.49. Valisnieri i. 101.t.vi.f.4. &c.[283]Bibl. Nat.i. 149. a.t.xxix.f.a.Cuv.Anat. Comp.iv. 439. Malpigh.De Bombyc.t.iii.f.2.[284]Sur le Vol des Ins.c. ii. 336. note 1.[285]Swamm.Bibl. Nat.t.xvii.f.9. CuvierIbid.440.[286]PlateXXIX.Fig.10.a.[287]Ibid.b.[288]De Geer vi. 374.[289]Reaum. v. 40.t.vi.f.4, 7.[290]SprengelComment.4.[291]De Geer ii. 667, 675.[292]Reaum. vi. 394—.[293]Reaum. vi. 394—. Cuv.Anat. Comp.iv. 440—.N. Dict. d'Hist. Nat.xvii. 540—.[294]PlateXXIX.Fig.9.a, b.Reaum. vi. 418—. 450.[295]Cuv.Anat. Comp.iv. 441.[296]Vol.III. p.583.[297]SprengelComment.17.t.iii.f.24.[298]Ibid.t.i.f.11.[299]Sur le Vol des Ins.c. ii. 336. note 1.[300]SprengelComment.13—. Theseosculaor pores in the straw ofTriticum hybernum, as figured by Mr. Bauer's admirable pencil, (Sir J. BanksOn the Blight, &c.t.ii.f.3.) exactly resemble the spiracles of insects.[301]Reaum. i. 136.[302]BonnetŒuvr.iii. 39—.[303]Ibid.43.[304]Ibid.50.[305]Ibid.69.[306]De Geer ii. 117.[307]See above, p.50.[308]Reaum. iv. 520.[309]Mr. B. Clark thinks that he has discovered spiracles in this larva in the usual situation, (Essay on the Bots, &c.48.t.ii.f.3.) but they are probably analogous to the spiraculiform tubercles ofŒ. Ovis. Reaum. iv. 566.t.xxxv. 17-19. t. Vallisnieri (Esperienz. &c.136) notices them.[310]Sur le Vol des Ins.c. i. 423.[311]Ibid.454. and c. iv. 66. note 1.[312]Ibid.c. i. 453.[313]Ibid.459, 456.[314]Ibid.459.[315]Annal. de Chim.xii.[316]Sur le Vol des Ins.c. i. 423, 454. c. iii. 344. c. iv. 66.[317]De Geer ii. 946—.[318]Lesser, L. i. 124. note *. LyonetAnatom.pref. xii. De Geer ii. 132.[319]Reaum. i. 399—. De Geer i. 37—.[320]Ibid.40.[321]Reaum. i. 400.[322]Ibid.[323]De Geer ii. 129.[324]De Geer i. 531—.t.xxxvii.f.13. s. Compare Reaum. ii. 396—.[325]See above, p.51—.[326]InLinn. Trans.iii. 302.[327]Vol.III. p.195—.[328]Spallanzani found that the eggs of insects placed under the exhausted receiver of an air-pump, or in any small closed vessels, did not hatch, though every other condition for their development was present.Opusc. de. Phys.i. 141.[329]Philos. Trans.1820. 213.[330]Bibl. Nat.i. 204. b.t.xix.f.5.[331]Vol.I. p.446—. III. p.76.[332]Ibid.68—.[333]Philos. Trans.1820. 218.[334]Vol.III. p.94.[335]Vol.II. p.228—.[336]Ibid. p.211.[337]Inch, c. iv.Ideen zu Einer Zoochemie, 68—.[338]On Thermom.141.[339]Carlisle inPhilos. Trans.1805. 25.[340]Vol.II. p.229.[341]Travelsii. 482.[342]Reaum. v. 540.[343]Swamm.Bibl. Nat.ii. 65. a.[344]Ibid.48. a.[345]Hist. Nat.l.xi.c.19.[346]Swamm.Bibl. Nat.ii. 64. a.[347]Reaum. iv. 428.t.xxix.f.2.c, s.[348]Genes.ix. 4.[349]N. Dict. d'Hist. Nat.xxx. 130.[350]Cuv.Anat. Comp.iv. 167.[351]HeroldSchmetterl.25. note *.Vol.III. p.53.[352]N. Dict. d'Hist. Nat.vii. 313. Cuv.Anat. Comp.iv. 411.[353]Ibid.419, 407.[354]Ibid.[355]Ibid.410.[356]PlateXXII.Fig.15.[357]LyonetAnat.105.[358]Ibid.425.[359]Ibid.105—.[360]De Bombyc.15—.[361]Reaum. i. 160—.[362]Cuv.Anat. Comp.iv. 418.[363]Marcel de SerresMem. du Mus.1819. 69.[364]Swamm.Bibl. Nat.t.xl.f.4.t.xv.f.4.[365]De Bombyc.t.iii.f.4.[366]Ubi supr.414.[367]Ibid.425—.[368]Ibid.419.[369]Ibid.412.[370]LyonetAnat.413.[371]LyonetIbid.426. Cuv.Anat. Comp.iv. 419.[372]Lyonet says (426), "au-delà de trois millions de fois plus petits qu'un grain de sable"!![373]Ibid.[374]His words are—"In silkworms I have clearly seen various small vessels spring from and approaching to the heart, which I have even filled with a coloured liquid. But whether they were veins or arteries I cannot yet affirm." i. 112. a. 176. a. According to Cuvier (Anat. Comp.iv. 418), but I cannot find the passage, Swammerdam also mentions having seen a red fluid issue from small vessels in grasshoppers.[375]Reaum. v. 103.[376]Bonnet ii. 309. Perhaps in both cases the alimentary canal was the organ seen.[377]Reaum. iv. 171—.[378]Lesser L. ii. 84. note.[379]De Geer ii. 505—. vi. 287.[380]On the Microscope.i. 130.[381]Ibid.[382]Sur le Vol des Ins.325—.[383]LyonetAnat.427—.[384]Cuv.Anat. Comp.iv. 418—.[385]Mem. du Mus.1819. 71.[386]N. Dict. d'Hist. Nat.xvi. 208.[387]Marcel de Serres, in hisObservations on the Dorsal Vessel of Insects[388], endeavours to prove that the principal use of that vessel is the more perfect animalization of the chyle that, transuding through the pores of the intestinal canal, is imbibed by it. In insects, he observes, that undergo metamorphoses, in which the growth or development of parts is often very rapid, it is requisite that a considerable portion of the chyle should be in reserve for this purpose. On this account it is that theEpiploonor adipose tissue is so abundant in larvæ to what it is in the perfect insect. That the importance also of this part to insects is proved by the circumstance, that all their interior parts communicate by fibrils with this tissue, and that probably their various organs derive the nutriment from it by their means. He then asks by which of the viscera is the fat elaborated, or by what means does the chyle which transudes from the intestinal canal pass to the state of fat? Facts seem to indicate, says he, that the function of the dorsal vessel is to pump up the chyle, and to cause it then to transude through the meshes of the adipose tissue, where it finishes by elaborating that mass of fat so abundant in larvæ and certain perfect insects, which are thus enabled to sustain the effects of a long fast. So that this vessel is only asecretoryorgan, analogous to so many others that exist in insects; but the secretion which it has to produce is the most important of all, since the support of the vital powers depends upon it: it is, in effect, that vessel which completes the function of animalization, and which itself prepares the nutritive fluid[389]. He observes, amongst other reasons he brings to support his theory, that the colour of the fluid which it contains is always analogous to that of the adipose tissue that surrounds it, and that the colour of that tissue never changes without that of the fluid undergoing a corresponding alteration,—that when, as in many perfect insects, the quantity of fat diminishes, the dorsal vessel also diminishes in size, and that the same reagents which coagulate the fat, coagulate equally the fluid in the dorsal vessel, which seems to indicate an identity between them[390].But there are circumstances that militate against this hypothesis. The analysis which Lyonet has given of the fluid contained in the dorsal vessel of theCossus[391], seems to prove that it is more analogous to gum or varnish. He saw indeed a few globules, which appeared ten times as big as the others, which swam upon the water, but which he did not regard as component parts of the fluid, but as little drops of grease extravasated by dissection. The fluid of the vessel itself easily mixed with water, and appeared to sink in it to the bottom[392]. This proves that it is not of a fatty or oleaginous nature. But the strongest objection is stated by M. Carus, who judiciously observes[393], That it is contradictory to suppose that a canal should absorb or exude fluids by its parietes in a different form. Further experiments however seem necessary to ascertain the nature of the fluid and its object.[388]Mem. du Mus.1819.[389]Ibid.68—.[390]Ibid.69—.[391]See above, p.85.[392]LyonetAnat.426—.[393]Introd. to Comp. Anat.ii. 277. Engl. Trans.[394]This seems some confirmation of Dr. Virey's opinion, that insects in their first states are still a kind offœtus. See above,Vol.III. p.61—.[395]Introd. to Comp. Anat.ii. 393—. Engl. Trans.[396]Introd. to Comp. Anat.ii. 395—. Engl. Trans.[397]Introd. to Comp. Anat.ii. 396—. Engl. Trans.[398]Ibid.398.[399]Ibid.399.[400]Ibid.398.[401]Introd. to Comp. Anat.ii. 399—. Engl. Trans.[402]Reaum. i. 409, 643—. Malpigh.De Bombyc.38.[403]Lesser L. ii. 87 note *.[404]Ubi supra.[405]Reaumur iv. 264.[406]Ibid. 260—.[407]HeroldSchmetterl. 24.[408]Anat. Comp.iv. 165.[409]Marcel de Serres (p. 67.) speaks of this fluid as being, after it has transuded through the intestinal canal, a fluid inrepose, which seems to indicate that it is perfectlystagnant; but when we consider that it is not only incessantly entering the body and making its way to every part, but is also, by means of the various secretory organs, constantly converted into new products, and so going out again in many cases, it will appear evident that it cannot be considered as a stagnant fluid, since there must be a constant though probably slow motion towards the points of absorption or imbibition.[410]Dr. Kidd (Philos. Trans.1825. 236.) did not find the abdominal viscera of the mole-cricket thus circumstanced, nor more lubricated than the intestines of the higher animals.[411]Cuv.Anat. Comp.iv. 158. HeroldSchmetterl.28.[412]Sur le Vol des Ins.c. iv. 88. note 1.[413]Anat.428.[414]TreviranusArachnid.28.t.iii.f.28, 29.[415]Ibid.29.t.iii.f.30, 31.[416]N. Dict. d'Hist. Nat.xxx. 420. Comp. Treviran.Arachnid.10—.[417]Ibid.9—.[418]Anat. Comp.iv. 129.[419]Cuv.Anat. Comp.iv. 129.[420]PlateXXI.Fig.3. c, d, e, is the intestinal canal of the larva of theCossus.[421]Cuv.Ibid.112.[422]RamdohrAnat. der Ins.6.[423]Ibid.25.[424]Ibid.6.[425]Cuv.ubi supr.113.[426]Comp. RamdohrAnat.7.[427]PlateXXI.Fig.3.c.[428]TenebrioRamdohr,ubi supr.9.t.iv.f.1.[429]Agrion.Ibid.t.xv.f.4.a, b.[430]Ibid.[431]Many other insects that live by suction have something similar, as the honey-bag of butterflies,PlateXXX.Fig.10, 11.a.Ramdohrt.xviii.f.2. witht.xix.f.1-3. and xxi. 1, 3, &c.[432]RamdohrAnat.11—.[433]PlateXXI.Fig.3.d.[434]RamdohrIbid.28—.[435]Herold (Schmetterl.24) says that Ramdohr is mistaken here, and denies the existence of this juice in insects; but as Ramdohr's researches were so widely extended, he is most likely to be right.[436]RamdohrIbid.29.[437]Ibid.31.[438]Ibid.28.[439]Anat. Comp.iv. 135. Comp. Dr. Kidd inPhilos. Trans.1825. 223.t.xv.f.6, 7.[440]RamdohrAnat.15.[441]Ibid.15.[442]Ibid.18.[443]Ibid.[444]Ibid.[445]Swamm.Bibl. Nat.i. 94. b. Cuv.Anat. Comp.iv. 134.[446]Ubi supr.18.[447]Ibid.t.i.f.1.e.5.c.9.g, h.[448]Ibid.t.xxv.f.4.bb.[449]RamdohrAnat.t.viii.f.3.cc.[450]Ibid.t.vii.f.2.[451]Ibid.20.[452]Anat. Comp.iv. 132.[453]Ibid.and 136.[454]Ubi supr.30.[455]Ibid.31.t.iv.f.2.c.t.v.f.1.d. f.4. D.[456]Ibid.32.[457]Ibid.34.[458]RamdohrAnat.35.[459]Ibid.t.xxiv.f.1.F.[460]Ibid.36.t.vii.f.2.kk.t.viii.f.3.g, hh.[461]Ibid.t.xii.f.1.t.xvii.f.1.t.vii.f.5.[462]Ibid.37.[463]Ibid.38.[464]Ibid.[465]RamdohrAnat.40.[466]De Bombyc.18—.[467]Anat. Comp.iv. 153.[468]Ibid.[469]Ibid.[470]Ramdohr 43.Cicindela campestris,t.iii.f.1. K.[471]Phryganea grandis,Ibid.t.xvi.f.2.[472]Notonecta glauca,Ibid.t.xxiii.f.5.[473]OfMusca vomitoria,Ibid.t.xix.f.5.[474]Ibid.t.viii.f.1. H. and G.f.2.[475]Ibid.50.[476]Ibid.[477]Ibid.[478]Ibid.44.t.i.f.9.[479]Ibid.[480]Ibid.t.vi.f.5. H.[481]Kidd inPhilos. Trans.1825.t.xv.f.6.[482]Ibid.t.xix.f.1.N, N, O,f.2.P, P, O.[483]Ibid.t.1.f.1.kkk.[484]Ramdohr,t.xiii.f.1-3.[485]Ibid.44.[486]Ibid.45.[487]Ibid.45.PlateXXI.Fig.3.f. f.[488]Rhamdohr,Ibid.t.iii.f.6. E.[489]Ibid.t.i.f.1. 5. 9.t.xiv.f.1-3.[490]Ibid.46.t.vi.f.3.[491]Ramdohr,t.vii.f.2.[492]Ibid.t.ii. iii. &c.t.xx.f.1, 2. 6.t.xxii.f.1-5. &c.[493]Ibid.t.xviii.f.1. 5.t.iv.f.1. See alsot.vi.f.1. 3.[494]Ibid.Anat.t.xvii.f.1, 2. 6.[495]Ibid.t.xiv.f.3.[496]Ibid.t.xiii.f.4.[497]Ibid.t.xv.f.3, 4.t.1.f.1. 5. 9.t.xii.f.4, 5, 6, &c.[498]Ibid.t.xi.f.4.t.xii.f.4-6.t.xiii.f.2-4, &c.[499]Ibid.t.vii.f.1.t.viii.f.1, &c.[500]RamdohrAnat.t.ii. iii. xxv.[501]Ibid.t.iii.f.6.t.iv.f.2.t.v.f.1.[502]Ibid.f.l.e. f.3.[503]Ibid.122.[504]Ibid.123.[505]Ibid.t.v.f.4. B.[506]Ibid.94.[507]Ibid.96—.[508]Ramdohrt.x.f.1. 8.[509]Ibid.f.8.b. c.[510]Ibid.98.t.x.f.2-4. From Ramdohr's figure, compared with the size of the insect, it appears that the gizzard could scarcely have been of greater diameter.[511]Ibid.f.2.[512]See W. Curtis inLinn. Trans.i. 88.[513]Ramdohrt.x.f.1.d.[514]Ibid.l l.[515]Ibid.t.ix.f.1, 2.t.xi.f.3.t.xxiv.f.1, 2.[516]Ramdohr 103.[517]Ibid.104.t.vi.f.4. D.[518]Ibid.f.2. B.[519]Ibid.t.vi.f.3. E.[520]Ibid.101.[521]Ibid.t.i.f.1. 5. 9.[522]Ibid.f.2, 3, 4. 7, 8. 12.[523]Ibid.f.1.e,f.5.c.f.9.g h.[524]Ibid.f.1. 9.k.[525]Ibid.t.xv.f.3, 4.t.xvii.f.2. 6.[526]Ibid.t.xv.f.3, 4,f.[527]Ibid.t.xvii.f.2.c.f.6.d.[528]Ibid.f.2.b.f.6.c.[529]Ramdohrt.xii.f.6.H.t.xiii.f.1.f.[530]Ibid.t.xiv.f.2, 3,C.
[258]TreviranusArachnid.7—.t.l.f.1.r. f.10. Comp.N. Dict. d'Hist. Nat.xxx. 419. Latreille calls these gillsPneumo-branches.
[259]TreviranusIbid.24.PlateXXIX.Fig.1.
[260]PlateXXI.Fig.3.a b.
[261]Ibid.a.
[262]Ibid.b.
[263]SprengelCommentar.t.i.f.1.
[264]Ibid.f.10.
[265]Ibid.t.ii.f.15.
[266]Malpigh.De Bombyc.t.iii.f.3.
[267]Ibid.t.iv.f.1.
[268]LyonetAnat.101.
[269]LyonetAnat.101.
[270]Sprengel (ubi. supr.16.) says that he never found more thantwo; but as Lyonet affirms that he has very often separated them (102), his accuracy cannot be questioned.
[271]LyonetAnat.103.
[272]Ibid.Cuv.Anat. Comp.iv. 438. This author says that theintermediatetunic is the spiral thread (437).
[273]Lyonet 102.
[274]Ibid. 104. SprengelCommentar.17.
[275]Lyonet 104. SprengelCommentar.17.
[276]Lyonet 102. Malpigh.De Bombyc.12. Reaum. i. 130.
[277]Swamm.Bibl. Nat.t.ii.f.7.
[278]Lyonet 411.
[279]Professor Kidd (Philos. Trans.1825. 235.) conjectures that the tracheæ, as well as air-vessels, may possibly be blood-vessels; but this hypothesis is inconsistent with the fact recently discovered by Dr. Carus, of a circulation, by other means, in larvæ. See CarusIntrod. to Comp. Anat.&c. ii. 400.
[280]N. Dict. d'Hist. Nat.xvii. 541. Reaum. vi. 397.PlateXXIX.Fig.8. showsthreeof them ata.
[281]Essay on the Bots, &c.23.t.i.f.7, 32, &c.
[282]Ibid.49. Valisnieri i. 101.t.vi.f.4. &c.
[283]Bibl. Nat.i. 149. a.t.xxix.f.a.Cuv.Anat. Comp.iv. 439. Malpigh.De Bombyc.t.iii.f.2.
[284]Sur le Vol des Ins.c. ii. 336. note 1.
[285]Swamm.Bibl. Nat.t.xvii.f.9. CuvierIbid.440.
[286]PlateXXIX.Fig.10.a.
[287]Ibid.b.
[288]De Geer vi. 374.
[289]Reaum. v. 40.t.vi.f.4, 7.
[290]SprengelComment.4.
[291]De Geer ii. 667, 675.
[292]Reaum. vi. 394—.
[293]Reaum. vi. 394—. Cuv.Anat. Comp.iv. 440—.N. Dict. d'Hist. Nat.xvii. 540—.
[294]PlateXXIX.Fig.9.a, b.Reaum. vi. 418—. 450.
[295]Cuv.Anat. Comp.iv. 441.
[296]Vol.III. p.583.
[297]SprengelComment.17.t.iii.f.24.
[298]Ibid.t.i.f.11.
[299]Sur le Vol des Ins.c. ii. 336. note 1.
[300]SprengelComment.13—. Theseosculaor pores in the straw ofTriticum hybernum, as figured by Mr. Bauer's admirable pencil, (Sir J. BanksOn the Blight, &c.t.ii.f.3.) exactly resemble the spiracles of insects.
[301]Reaum. i. 136.
[302]BonnetŒuvr.iii. 39—.
[303]Ibid.43.
[304]Ibid.50.
[305]Ibid.69.
[306]De Geer ii. 117.
[307]See above, p.50.
[308]Reaum. iv. 520.
[309]Mr. B. Clark thinks that he has discovered spiracles in this larva in the usual situation, (Essay on the Bots, &c.48.t.ii.f.3.) but they are probably analogous to the spiraculiform tubercles ofŒ. Ovis. Reaum. iv. 566.t.xxxv. 17-19. t. Vallisnieri (Esperienz. &c.136) notices them.
[310]Sur le Vol des Ins.c. i. 423.
[311]Ibid.454. and c. iv. 66. note 1.
[312]Ibid.c. i. 453.
[313]Ibid.459, 456.
[314]Ibid.459.
[315]Annal. de Chim.xii.
[316]Sur le Vol des Ins.c. i. 423, 454. c. iii. 344. c. iv. 66.
[317]De Geer ii. 946—.
[318]Lesser, L. i. 124. note *. LyonetAnatom.pref. xii. De Geer ii. 132.
[319]Reaum. i. 399—. De Geer i. 37—.
[320]Ibid.40.
[321]Reaum. i. 400.
[322]Ibid.
[323]De Geer ii. 129.
[324]De Geer i. 531—.t.xxxvii.f.13. s. Compare Reaum. ii. 396—.
[325]See above, p.51—.
[326]InLinn. Trans.iii. 302.
[327]Vol.III. p.195—.
[328]Spallanzani found that the eggs of insects placed under the exhausted receiver of an air-pump, or in any small closed vessels, did not hatch, though every other condition for their development was present.Opusc. de. Phys.i. 141.
[329]Philos. Trans.1820. 213.
[330]Bibl. Nat.i. 204. b.t.xix.f.5.
[331]Vol.I. p.446—. III. p.76.
[332]Ibid.68—.
[333]Philos. Trans.1820. 218.
[334]Vol.III. p.94.
[335]Vol.II. p.228—.
[336]Ibid. p.211.
[337]Inch, c. iv.Ideen zu Einer Zoochemie, 68—.
[338]On Thermom.141.
[339]Carlisle inPhilos. Trans.1805. 25.
[340]Vol.II. p.229.
[341]Travelsii. 482.
[342]Reaum. v. 540.
[343]Swamm.Bibl. Nat.ii. 65. a.
[344]Ibid.48. a.
[345]Hist. Nat.l.xi.c.19.
[346]Swamm.Bibl. Nat.ii. 64. a.
[347]Reaum. iv. 428.t.xxix.f.2.c, s.
[348]Genes.ix. 4.
[349]N. Dict. d'Hist. Nat.xxx. 130.
[350]Cuv.Anat. Comp.iv. 167.
[351]HeroldSchmetterl.25. note *.Vol.III. p.53.
[352]N. Dict. d'Hist. Nat.vii. 313. Cuv.Anat. Comp.iv. 411.
[353]Ibid.419, 407.
[354]Ibid.
[355]Ibid.410.
[356]PlateXXII.Fig.15.
[357]LyonetAnat.105.
[358]Ibid.425.
[359]Ibid.105—.
[360]De Bombyc.15—.
[361]Reaum. i. 160—.
[362]Cuv.Anat. Comp.iv. 418.
[363]Marcel de SerresMem. du Mus.1819. 69.
[364]Swamm.Bibl. Nat.t.xl.f.4.t.xv.f.4.
[365]De Bombyc.t.iii.f.4.
[366]Ubi supr.414.
[367]Ibid.425—.
[368]Ibid.419.
[369]Ibid.412.
[370]LyonetAnat.413.
[371]LyonetIbid.426. Cuv.Anat. Comp.iv. 419.
[372]Lyonet says (426), "au-delà de trois millions de fois plus petits qu'un grain de sable"!!
[373]Ibid.
[374]His words are—"In silkworms I have clearly seen various small vessels spring from and approaching to the heart, which I have even filled with a coloured liquid. But whether they were veins or arteries I cannot yet affirm." i. 112. a. 176. a. According to Cuvier (Anat. Comp.iv. 418), but I cannot find the passage, Swammerdam also mentions having seen a red fluid issue from small vessels in grasshoppers.
[375]Reaum. v. 103.
[376]Bonnet ii. 309. Perhaps in both cases the alimentary canal was the organ seen.
[377]Reaum. iv. 171—.
[378]Lesser L. ii. 84. note.
[379]De Geer ii. 505—. vi. 287.
[380]On the Microscope.i. 130.
[381]Ibid.
[382]Sur le Vol des Ins.325—.
[383]LyonetAnat.427—.
[384]Cuv.Anat. Comp.iv. 418—.
[385]Mem. du Mus.1819. 71.
[386]N. Dict. d'Hist. Nat.xvi. 208.
[387]Marcel de Serres, in hisObservations on the Dorsal Vessel of Insects[388], endeavours to prove that the principal use of that vessel is the more perfect animalization of the chyle that, transuding through the pores of the intestinal canal, is imbibed by it. In insects, he observes, that undergo metamorphoses, in which the growth or development of parts is often very rapid, it is requisite that a considerable portion of the chyle should be in reserve for this purpose. On this account it is that theEpiploonor adipose tissue is so abundant in larvæ to what it is in the perfect insect. That the importance also of this part to insects is proved by the circumstance, that all their interior parts communicate by fibrils with this tissue, and that probably their various organs derive the nutriment from it by their means. He then asks by which of the viscera is the fat elaborated, or by what means does the chyle which transudes from the intestinal canal pass to the state of fat? Facts seem to indicate, says he, that the function of the dorsal vessel is to pump up the chyle, and to cause it then to transude through the meshes of the adipose tissue, where it finishes by elaborating that mass of fat so abundant in larvæ and certain perfect insects, which are thus enabled to sustain the effects of a long fast. So that this vessel is only asecretoryorgan, analogous to so many others that exist in insects; but the secretion which it has to produce is the most important of all, since the support of the vital powers depends upon it: it is, in effect, that vessel which completes the function of animalization, and which itself prepares the nutritive fluid[389]. He observes, amongst other reasons he brings to support his theory, that the colour of the fluid which it contains is always analogous to that of the adipose tissue that surrounds it, and that the colour of that tissue never changes without that of the fluid undergoing a corresponding alteration,—that when, as in many perfect insects, the quantity of fat diminishes, the dorsal vessel also diminishes in size, and that the same reagents which coagulate the fat, coagulate equally the fluid in the dorsal vessel, which seems to indicate an identity between them[390].
But there are circumstances that militate against this hypothesis. The analysis which Lyonet has given of the fluid contained in the dorsal vessel of theCossus[391], seems to prove that it is more analogous to gum or varnish. He saw indeed a few globules, which appeared ten times as big as the others, which swam upon the water, but which he did not regard as component parts of the fluid, but as little drops of grease extravasated by dissection. The fluid of the vessel itself easily mixed with water, and appeared to sink in it to the bottom[392]. This proves that it is not of a fatty or oleaginous nature. But the strongest objection is stated by M. Carus, who judiciously observes[393], That it is contradictory to suppose that a canal should absorb or exude fluids by its parietes in a different form. Further experiments however seem necessary to ascertain the nature of the fluid and its object.
[388]Mem. du Mus.1819.
[389]Ibid.68—.
[390]Ibid.69—.
[391]See above, p.85.
[392]LyonetAnat.426—.
[393]Introd. to Comp. Anat.ii. 277. Engl. Trans.
[394]This seems some confirmation of Dr. Virey's opinion, that insects in their first states are still a kind offœtus. See above,Vol.III. p.61—.
[395]Introd. to Comp. Anat.ii. 393—. Engl. Trans.
[396]Introd. to Comp. Anat.ii. 395—. Engl. Trans.
[397]Introd. to Comp. Anat.ii. 396—. Engl. Trans.
[398]Ibid.398.
[399]Ibid.399.
[400]Ibid.398.
[401]Introd. to Comp. Anat.ii. 399—. Engl. Trans.
[402]Reaum. i. 409, 643—. Malpigh.De Bombyc.38.
[403]Lesser L. ii. 87 note *.
[404]Ubi supra.
[405]Reaumur iv. 264.
[406]Ibid. 260—.
[407]HeroldSchmetterl. 24.
[408]Anat. Comp.iv. 165.
[409]Marcel de Serres (p. 67.) speaks of this fluid as being, after it has transuded through the intestinal canal, a fluid inrepose, which seems to indicate that it is perfectlystagnant; but when we consider that it is not only incessantly entering the body and making its way to every part, but is also, by means of the various secretory organs, constantly converted into new products, and so going out again in many cases, it will appear evident that it cannot be considered as a stagnant fluid, since there must be a constant though probably slow motion towards the points of absorption or imbibition.
[410]Dr. Kidd (Philos. Trans.1825. 236.) did not find the abdominal viscera of the mole-cricket thus circumstanced, nor more lubricated than the intestines of the higher animals.
[411]Cuv.Anat. Comp.iv. 158. HeroldSchmetterl.28.
[412]Sur le Vol des Ins.c. iv. 88. note 1.
[413]Anat.428.
[414]TreviranusArachnid.28.t.iii.f.28, 29.
[415]Ibid.29.t.iii.f.30, 31.
[416]N. Dict. d'Hist. Nat.xxx. 420. Comp. Treviran.Arachnid.10—.
[417]Ibid.9—.
[418]Anat. Comp.iv. 129.
[419]Cuv.Anat. Comp.iv. 129.
[420]PlateXXI.Fig.3. c, d, e, is the intestinal canal of the larva of theCossus.
[421]Cuv.Ibid.112.
[422]RamdohrAnat. der Ins.6.
[423]Ibid.25.
[424]Ibid.6.
[425]Cuv.ubi supr.113.
[426]Comp. RamdohrAnat.7.
[427]PlateXXI.Fig.3.c.
[428]TenebrioRamdohr,ubi supr.9.t.iv.f.1.
[429]Agrion.Ibid.t.xv.f.4.a, b.
[430]Ibid.
[431]Many other insects that live by suction have something similar, as the honey-bag of butterflies,PlateXXX.Fig.10, 11.a.Ramdohrt.xviii.f.2. witht.xix.f.1-3. and xxi. 1, 3, &c.
[432]RamdohrAnat.11—.
[433]PlateXXI.Fig.3.d.
[434]RamdohrIbid.28—.
[435]Herold (Schmetterl.24) says that Ramdohr is mistaken here, and denies the existence of this juice in insects; but as Ramdohr's researches were so widely extended, he is most likely to be right.
[436]RamdohrIbid.29.
[437]Ibid.31.
[438]Ibid.28.
[439]Anat. Comp.iv. 135. Comp. Dr. Kidd inPhilos. Trans.1825. 223.t.xv.f.6, 7.
[440]RamdohrAnat.15.
[441]Ibid.15.
[442]Ibid.18.
[443]Ibid.
[444]Ibid.
[445]Swamm.Bibl. Nat.i. 94. b. Cuv.Anat. Comp.iv. 134.
[446]Ubi supr.18.
[447]Ibid.t.i.f.1.e.5.c.9.g, h.
[448]Ibid.t.xxv.f.4.bb.
[449]RamdohrAnat.t.viii.f.3.cc.
[450]Ibid.t.vii.f.2.
[451]Ibid.20.
[452]Anat. Comp.iv. 132.
[453]Ibid.and 136.
[454]Ubi supr.30.
[455]Ibid.31.t.iv.f.2.c.t.v.f.1.d. f.4. D.
[456]Ibid.32.
[457]Ibid.34.
[458]RamdohrAnat.35.
[459]Ibid.t.xxiv.f.1.F.
[460]Ibid.36.t.vii.f.2.kk.t.viii.f.3.g, hh.
[461]Ibid.t.xii.f.1.t.xvii.f.1.t.vii.f.5.
[462]Ibid.37.
[463]Ibid.38.
[464]Ibid.
[465]RamdohrAnat.40.
[466]De Bombyc.18—.
[467]Anat. Comp.iv. 153.
[468]Ibid.
[469]Ibid.
[470]Ramdohr 43.Cicindela campestris,t.iii.f.1. K.
[471]Phryganea grandis,Ibid.t.xvi.f.2.
[472]Notonecta glauca,Ibid.t.xxiii.f.5.
[473]OfMusca vomitoria,Ibid.t.xix.f.5.
[474]Ibid.t.viii.f.1. H. and G.f.2.
[475]Ibid.50.
[476]Ibid.
[477]Ibid.
[478]Ibid.44.t.i.f.9.
[479]Ibid.
[480]Ibid.t.vi.f.5. H.
[481]Kidd inPhilos. Trans.1825.t.xv.f.6.
[482]Ibid.t.xix.f.1.N, N, O,f.2.P, P, O.
[483]Ibid.t.1.f.1.kkk.
[484]Ramdohr,t.xiii.f.1-3.
[485]Ibid.44.
[486]Ibid.45.
[487]Ibid.45.PlateXXI.Fig.3.f. f.
[488]Rhamdohr,Ibid.t.iii.f.6. E.
[489]Ibid.t.i.f.1. 5. 9.t.xiv.f.1-3.
[490]Ibid.46.t.vi.f.3.
[491]Ramdohr,t.vii.f.2.
[492]Ibid.t.ii. iii. &c.t.xx.f.1, 2. 6.t.xxii.f.1-5. &c.
[493]Ibid.t.xviii.f.1. 5.t.iv.f.1. See alsot.vi.f.1. 3.
[494]Ibid.Anat.t.xvii.f.1, 2. 6.
[495]Ibid.t.xiv.f.3.
[496]Ibid.t.xiii.f.4.
[497]Ibid.t.xv.f.3, 4.t.1.f.1. 5. 9.t.xii.f.4, 5, 6, &c.
[498]Ibid.t.xi.f.4.t.xii.f.4-6.t.xiii.f.2-4, &c.
[499]Ibid.t.vii.f.1.t.viii.f.1, &c.
[500]RamdohrAnat.t.ii. iii. xxv.
[501]Ibid.t.iii.f.6.t.iv.f.2.t.v.f.1.
[502]Ibid.f.l.e. f.3.
[503]Ibid.122.
[504]Ibid.123.
[505]Ibid.t.v.f.4. B.
[506]Ibid.94.
[507]Ibid.96—.
[508]Ramdohrt.x.f.1. 8.
[509]Ibid.f.8.b. c.
[510]Ibid.98.t.x.f.2-4. From Ramdohr's figure, compared with the size of the insect, it appears that the gizzard could scarcely have been of greater diameter.
[511]Ibid.f.2.
[512]See W. Curtis inLinn. Trans.i. 88.
[513]Ramdohrt.x.f.1.d.
[514]Ibid.l l.
[515]Ibid.t.ix.f.1, 2.t.xi.f.3.t.xxiv.f.1, 2.
[516]Ramdohr 103.
[517]Ibid.104.t.vi.f.4. D.
[518]Ibid.f.2. B.
[519]Ibid.t.vi.f.3. E.
[520]Ibid.101.
[521]Ibid.t.i.f.1. 5. 9.
[522]Ibid.f.2, 3, 4. 7, 8. 12.
[523]Ibid.f.1.e,f.5.c.f.9.g h.
[524]Ibid.f.1. 9.k.
[525]Ibid.t.xv.f.3, 4.t.xvii.f.2. 6.
[526]Ibid.t.xv.f.3, 4,f.
[527]Ibid.t.xvii.f.2.c.f.6.d.
[528]Ibid.f.2.b.f.6.c.
[529]Ramdohrt.xii.f.6.H.t.xiii.f.1.f.
[530]Ibid.t.xiv.f.2, 3,C.