418 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1938 



the glandular debris was dried and weighed. The difference between 

 the two weights is taken to represent the dry weight of the venom. 

 This is not entirely correct, since unavoidably some glandular ele- 

 ments were lost in maceration. The figure obtained errs, therefore, 

 on the side of assigning a somewhat lower potency to the venom 

 than is actually the case. Table 8 shows the results. 



These results indicate that on the basis of weight the venom of the 

 black widow is extremely potent. In man, the spider bite results fatally 

 in about 5 percent of all cases (Bogen, 1932). The rattlesnake is said 

 to kill in from 15 to 25 percent; the actual amount of venom intro- 

 duced is, however, much greater in the case of the snake. Experi- 

 mentally, Calmette found that 0.2 mg of cobra vemon will kill a guinea 

 pig, and Noguchi states that 5 mg of rattlesnake venom will kill a 

 350-gram guinea pig in 24 hours. The following comparison of the 

 potency of black widow with rattlesnake venom was made. Two 

 specimens of the common prairie rattlesnake (Crotalus albicans, Say) 

 were collected, one a male 3 feet long with eight rattles and the other 

 a female 2% feet long with six rattles. The venom was obtained by 

 pressing upon the glands, then dissecting them out and washing 

 with distilled water and evaporating to dryness. Thirty-two mg of 

 dried venom were obtained from the large snake and 20 mg from the 

 small. The venoms were pooled and assayed. The results are given 

 in table 8a. 



As 0.064 mg of spider venom killed 90 percent of injected rats, it 

 appears to be about 15 times as potent on a dry-weight basis. 



Table 8a 



TOXICOLOGY 



Symptomatology. — The effect of the black widow spider venom upon 

 the organism has been variously described by different investigators. 

 In the human, Bogen (1932) has studied a considerable series of cases 

 and finds that the chain of symptoms is a remarkably constant one. 

 The outstanding features in the sequence of events are as follows: 

 The bite itself is not painful, being comparable to a sharp pin prick; 

 a dull numbing pain ascends the extremity bitten, and then localizes 

 itself in the muscles of the chest, back, and abdomen. This pain is 

 excruciating in character. The abdominal wall is boardlike in its 



