462 COLLECTED STUDIES IN IMMUNITY. 



VI. A Few Chemical Considerations. 



Finally, we should like briefly to discuss some of our experiences 

 with the power possessed by certain other substances to activate 

 cobra venom. In view of its content of lecithin, it will not surprise 

 us to know that bile activates cobra venom. It may be interesting, 

 however, to learn that goat milk acquires activating properties only 

 when it has previously been heated to 100 C. This behavior corre- 

 sponds entirely to that of certain species of sera whose lecithin does 

 not become available until after they have been heated to 65-100. 

 Among chemical substances we have found a number of fatty acids 

 and their soaps, chloroform, and olive oil able to activate to a cer- 

 tain degree. All these substances by themselves, however, dissolve 

 the blood-cells to a greater or less degree l and the increase of this 

 action is so slight that it is doubtful whether we can here speak 

 of pure activating phenomena. 2 



According to our experiences only one more substance, namely, 

 the lecithin-like cephalin, possesses marked activating properties. 

 (Cerebrin does not possess them.) For this cephalin we are indebted 

 to Waldemar Koch of Chicago, who made it from sheep's brain. 

 According to him, it is a dioxystearylmonomethyl lecithin. 3 The 

 cephalin (which is insoluble in alcohol) and the lecithin (which is 

 soluble in alcohol), both made by Koch from sheep's brains, further- 

 more two other preparations of lecithin (one from Riedel in Berlin, 

 the other kindly placed at our disposal by Dr. Bergell), all these 

 manifested a hsemolytic action (if at all) only in 500-600 times the 

 amount sufficient to activate the cobra venom. 



A preparation of lecithin derived from leguminous seeds, for 

 we are indebted to Prof. Schulze of Zurich, showed less dif- 

 ference between activating power and hsemolytic action, but even 



1 It is possible that the coctostable hsemolysins (soluble in alcohol-ether) 

 of the organ extracts belong in the same class with these substances (see 

 Korschun and Morgenroth, page 267). 



7 It must always be borne in mind that the activating property of these sub- 

 stances may possibly only be an indirect one, the presence of the substance 

 sufficing to make available the lecithin always present in the blood-cells in 

 combination. 



' W. Koch, Zur Kenntniss des Lecithins, Cephalins und Cerebrins aus Nerven- 

 substanz, Zeitsch. f physiol. Chemie, Vol. 36, Nos 2 and 3, 1903. 



