Etiology : Causes of Disease. 



15 



diatase is inapplicable, as the diatase is produced by the living 

 cells of the germinal part of the seed, which are thus the coun- 

 terpart of the disease germ. No such glycogenic action occurs 

 in the seed that has been boiled or otherwise robbed of its vital- 

 ity. So with the arguments drawn from the ptyaline of the sa- 

 liva, the pepsin of the gastric juice, and the trypsin of the pancre- 

 atic juice ; each of these is the product of the living cells of the 

 gland by which it is secreted, and cannot increase its own sub- 

 stance in the absence of these cells. Like the enzyme of the 

 bacteridian ferment, these gland products can break down or di- 

 gest certain organic matters, but in all alike, the only source of 

 the chemical solvent is the living bacterium or gland cell from 

 which the particular product is derived. The toxins of a viru- 

 lent liquid, after the sterilization of the latter may still produce 

 most of the lesions and morbid phenomena of the disease, but, 

 although death were to ensue, the body of the victim would not 

 be infecting to other susceptible animals. The parallel between 

 the functions of the secreting animal cells and the disease germs 

 may thus be put in tabular form : 



Living Source. Chemical Product. 



Salivary gland cells = Ptyaline 



Result, 

 changed 



to 



Peptic gland cells = Pepsin 



Pancreatic gland cells = Trypsin 



= Starch 

 Sugar. 

 = Albuminoids chang- 

 ed to peptones in 

 acid solutions. 

 = Albuminoids chang- 

 ed to peptones in 

 alkaline solutions. 

 Toxin : Enzyme = Morbid phenomena . 

 Contagious disease. 

 Further consideration of pathogenic microorganisms will be 

 found in connection with contagious diseases. 



Disease germ 

 Disease germ 



