174 COLLECTED STUDIES IN IMMUNITY. 



that although he found the haemolytic action to be present in the latter, "it 

 was much less than that of Karakurtes poison." It is possible, however, 

 that Kobert made these experiments on one of the species of blood found by 

 us to be insensitive to arachnolysin (horse blood, dog blood?). At any rate 

 our garden-spider extract far exceeds in hsemolytic action the Karakurtes poison 

 tested by Kobert in this respect. I should also like to point out that for the 

 haemolytic experiments with Karakurtes poison, Kobert used dog blood, which 

 according to our table belongs to the class of blood species immune to garden- 

 spider poison. Perhaps in conformity with the extensive analogy between 

 these two spider poisons, the Karakurtes poison possesses a far greater haemo- 

 lytic action on other species of blood. Kobert' s observation that a tolerance 

 can be established against Karakurtes poison as well as against garden-spider 

 poison, agrees very well with the idea of a strong antitoxic serum, a fact actually 

 observed by us. Since then we have obtained such a serum also in rabbits. 



