THE LEUCOCYTES IN IMMUNITY. 729 



gested by this cell included bacteria, these would become, there- 

 fore, the source of the bactericidal granules, according to 

 Ehrlich's theory. That such is not the case we have seen. 



To the question: "What is the physiological mechanism 

 called into action in the processes resulting in the production 

 of antitoxins, cytolysins, and similar bodies?" Ehrlich is stated 

 by Welch, however, to answer: "The mechanism is one physio- 

 logically employed for the assimilation by the cells of food. 

 The receptors are in the Icells, not for the purpose of linking 

 poisons to the cells, but to seize certain foodstuffs, particularly 

 the proteids, and the toxins and bacterial and other foreign 

 cellular substances, if capable of inducing the immunizing re- 

 action, chance to have the requisite combining affinities for the 

 food-receptors." There is obviously considerable analogy be- 

 tween this and our own interpretation, although the latter is 

 devoid of the complex questions introduced by specific affinities. 

 The cellular trypsin seems to us to be endowed with all the 

 bactericidal and toxin-destroying power required. Indeed, 

 trypsins appear to us to embody the functions attributed to all 

 the complements: Buchner^s alexin, and Metchnikoff's cytase, 

 while the oxidizing substance corresponds with Ehrlich's am- 

 boceptor: i.e., Bordet's sensitizing substance, or fixative. 



We are also vividly reminded of the fluctuations of adrenal 

 activity by the following words of Professor Welch's: "We 

 know that the content of the blood in specific anti-bodies, and 

 especially in complements, varies in significant ways under di- 

 verse conditions, as in infancy and in adult life, in health, in 

 different states of nutrition, under the influence of fatigue, of 

 inanition, of pain, of interference with respiration, of alcohol, 

 and in disease." 



We likewise find confirmation of the view we have sub- 

 mitted as to the causes of the vulnerability of children to in- 

 fectious diseases: i.e., inadequate protection through lack of 

 adrenal development, in the following lines by the same au- 

 thor: "The infant comes into the world with protective anti- 

 bodies in the blood smaller in amount and less energetic than 

 those possessed by the healthy adult. It is an important func- 

 tion of the mother to transfer to the suckling through her milk 

 immunizing bodies, and the infant's stomach has the capacity, 



