1 6 Poisonous Arthropods 



Robert therefore sought to prepare extracts which would contain 

 the active principles of the poison and which could be injected in 

 definite quantities directly into the blood of the experimental animal. 

 For this purpose various parts of the spiders were rubbed up in a mor- 

 tar with distilled water, or physiological salt solution, allowed to 

 stand for an hour, filtered, and then carefully washed, by adding water 

 drop by drop for twenty-four hours. The filtrate and the wash- 

 water were then united, well mixed and, if necessary, cleared by cen- 

 trifuging or by exposure to cold. The mixture was again filtered, 

 measured, and used, in part, for injection and, in part, for the deter- 

 mination of the organic materials. 



Such an extract was prepared from the cephalothoraces of eight 

 dried specimens of the Russian Latrodectus and three cubic centimeters' 

 of this, containing 4.29 mg. of organic material, were injected into 

 the jugular vein of a cat weighing 2450 grams. The previously very 

 active animal was paralyzed and lay in whatever position it was 

 placed. The sensibility of the skin of the extremities and the rump 

 was so reduced that there was no reaction from cutting or sticking. 

 There quickly followed dyspnoea, convulsions, paralysis of the 

 respiratory muscles and of the heart. In twenty-eight minutes the 

 cat was dead, after having exhibited exactly the symptoms observed 

 in severe cases of poisoning of man from the bite of this spider. 



These experiments were continued on cats, dogs, guinea pigs and 

 various other animals. Not only extracts from the cephalothorax, 

 but from other parts of the body, from newly hatched spiders, and 

 from the eggs were used and all showed a similar virulence. Every 

 effort was made to avoid sources of error and the experiments, con- 

 ducted by such a recognized authority in the field of toxicology, must 

 be accepted as conclusively showing that this spider and, presumably, 

 other species of the genus Latrodectus against which the clinical evi- 

 dence is quite parallel, possess a poison which paralyzes the heart and 

 central nervous system, with or without preliminary stimulus of the 

 motor center. If the quantity of the poison which comes into direct 

 contact with the blood is large, there may occur haemolysis and 

 thrombosis of the vessels. 



On the other hand, check experiments were carried out, using 

 similar extracts of many common European spiders of the genera 

 Tegenaria, Drassus, Agelena, Eucharia and Argyroneta, as well as 

 the Russian tarantula, Lycosa singoriensis. In no other case was the 

 effect on experimental animals comparable to the Latrodectus extract. 



