i6 
Poisonous Arthropods 
Kobert 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. I11 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 ihe 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- 
