THE POISON OF THE COMMON GARDEN SPIDER. 



169 



fore contains sufficient poison to completely destroy 2.5 liters rabbit 

 blood. Remembering that only an extremely small part of the 

 spider's weight is made up by the active poisonous constituent, 

 and even assuming that the content of arachnolysin amounts to 1%, 

 we see that this enormous activity indicates that the arachnolysin belongs 

 to the class of blood poisons which exert a powerful action after the man- 

 ner of the toxins. 



The same is indicated by the marked instabilty of the active 

 principle. Heat readily destroys the arachnolysin, although a higher 

 degree is necessary than for other haemolysins. Heating to 56 C. 

 for 40 minutes does not affect the poison solution, and at 60 C. 

 only a very slight reduction of action is noticed. Complete destruc- 

 tion does not occur until the poison is heated to 70-72 C. for 40 

 minutes. Arachnolysin is easily preserved by the addition of glyc- 

 erine, showing no reduction in activity even after months. 



Experiments, designed to show whether normal sera possess an 

 inhibiting action on haemolysis due to spider poison, have had nega- 



