454 COLLECTED STUDIES IN IMMUNITY. 



guinea-pig blood, for example, the lecithin is so loosely combined 

 that this blood can be used for activation. Hence, in speaking of 

 the lecithin action of animal tissues or juices, we refer only to the 

 lecithin which is free (available) in the sense just described; part 

 or all of the lecithin present may escape detection by means of the 

 activation of cobra venom. 



The fact that relatively slight alterations can cause the combina- 

 tion of lecithin to be either looser or firmer may be of some interest 

 in another direction. We have seen that the lecithin of many species 

 of sera becomes free only at 65 C., while the haemoglobin, on the other 

 hand, anchors the lecithin at 62 C. It is possible that during life 

 slight variations in the physical and chemical properties of the tissues 

 (variations which have heretofore been undetected) play an important 

 role in the sense that they properly regulate the exchange and trans- 

 portation of the lecithin so important for the vital functions. Dieu- 

 donne's 1 researches show that the albuminous bodies with which 

 the lecithin is combined (principally in the form of lecithalbumin) 

 are demonstrably modified, even at temperatures still quite distant 

 from their coagulation point. This author showed that B. coli, for 

 example, when inoculated into a serum lactose solution causes a 

 distinct precipitation even at 45 C., while this does not occur at 

 37 C. In the case of serum albumin, therefore, the temperature at 

 which this modification takes place is very near the temperature 

 which occurs in the living organism under pathological conditions. 

 In view of this and of the evident dependence of the physiological 

 behavior of the lecithin on the integrity of the albumin molecule, 

 one is tempted to see a causal relationship between febrile processes 

 and disturbances in lecithin metabolism. 



III. The Inhibitory Action of Cholesterin. 



The marked inhibitory action which many sera exert on haemolysis 

 with cobra venom and lecithin was described some time ago (Kyes, 

 1. c.) and the opinion then expressed that this protective action of the 

 serum was probably not due to a single substance but was the resultant 

 of several factors. Evidently we are here dealing with certain rela- 

 tions which exist between serum constituents and the lecithin, making 



1 Dieudonn6, Uber das Yerhalten des Bact coli zu nativem u. denaturir- 

 tem Eiweiss, Hyg. llundsch 1902, No. IS. 



