Transcriber's Note
Some presumed printer's errors have been corrected, including normalizing punctuation. Further corrections are listed below with the printed text (top) and corrected text (bottom):
to defect the approach of the diseaseto detect the approach of the disease (p.98)
to defect the approach of the diseaseto detect the approach of the disease (p.98)
to defect the approach of the diseaseto detect the approach of the disease (p.98)
to defect the approach of the disease
to detect the approach of the disease (p.98)