SUGAR IN THE NUTRIENT MEDIUM. 163 



the germs which are destroyed by the leucocytes is 

 absorbed by the latter secondarily, but some germs 

 are undoubtedly ingested alive by the leucocytes. 

 Metschnikoff the most redoubtable antagonist of 

 Buchner insists upon the view that the latter proc- 

 ess (phagocytosis), followed by subsequent death of 

 the germs within the leucocytes, is the essential fea- 

 ture of natural immunity. 



An increase of the congenital resistance to various 

 infectious diseases has been effected in a number of 

 ways. Thymus extract, spermin, abrin (toxic al- 

 buminoids from the paternoster pea), papayotin 

 (albumin-dissolving ferment from the papaya), cin- 

 namic acid, iodine trichloride, sodium carbonate, etc. , 

 when injected into animals have produced favorable 

 effects, sometimes in one, sometimes in several infec- 

 tious diseases. Indeed, an increased resistance has 

 been observed from the injection under the skin, but 

 especially into the peritoneal cavity, of an entire 

 series of ordinary albuminous substances, such as 

 blood serum and bouillon. 



It is generally assumed that this effect depends 

 upon increased stimulation of the leucocytes to the 

 production of substances which are antagonistic to 

 the bacteria. 



According to the majority of writers there is a 

 sharp contrast between this increased resistance and 

 the specific immunity from a definite disease which 

 develops when an individual has spontaneously ac- 

 quired and passed through this infectious disease or 

 when he has been purposely inoculated with : 



(1) Naturally or artificially attenuated infection- 

 producers of the same variety ; or 



