BLACK WIDOW SPIDER — D'AMOUR ET AL. 



413 



how long since it last made use of its poison apparatus and the speed 

 of regeneration of the poison — and upon the degree of anger aroused 

 by the pinching. As will be shown later, even under conditions 

 which one might suppose would excite the greatest degree of anger — 

 that is, after victory in mortal combat with another spider — the 

 glands still contain a considerable amount of venom. It seems likely 

 that the glands are under some degree of volitional control and the 

 amount ejected will depend upon the degree of irritation of the spider. 

 This is supported by the experience of Baerg (1922), who speaks of 

 spiders which bit readily and caused severe symptoms while others 

 attacked only under extreme provocation. 



As for the second method, that of using macerated heads as a source 

 of material, if a sufficiently large number of spiders is used, the size 

 and past history factors are averaged and, of course, the question of 

 degree of irritation does not enter. However, anyone who has ever 

 dissected out the venom glands will have noted their toughness and 

 elasticity. Macerating the heads, even though the operation is car- 

 ried out thoroughly, will certainly fail to crush all glands. An un- 

 known number will escape maceration and will then be discarded with 

 the debris. The following tables illustrate the above points. Table 

 1 gives the results of actual biting experiments. In these trials spiders 



Table 1 



were used which had been kept in the laboratory 3 days and had not 

 been fed during that period. These were placed upon shaved areas 

 of the rat's abdomen and excited to bite by being pinched with forceps. 

 The results are seen to be very inconsistent. 



In table 2 the results of two experiments are shown in which 

 macerated heads were used, 40 heads being used in each batch. The 

 wide variation in effect no doubt indicates failure to crush and extract 

 all glands. 



Comparison of these results with the toxicity curve for venom ob- 

 tained later indicates that even in the more active preparation a large 

 number of glands must have escaped extraction. 



