spiders of the Genus Latrodectus 15 



narcotics are desired. Warm baths give great relief. After three 

 days, there is marked improvement and usually the patient is dis- 

 missed after the fifth. This summary of symptoms agrees well with 

 other trustworthy records. 



It would seem, then, that Riley and Howard (i88g), who discussed 

 a nimiber of accounts in the entomological literature, were fully 

 justified in their statement that "It must be admitted that certain 

 spiders of the genus Latrodectus have the power to inflict poisonous 

 bites, which may (probably exceptionally and depending upon excep- 

 tional conditions) bring about the death of a human being." 



And yet, until recently the evidence bearing on the question has 

 been most conflicting. The eminent arachnologist, Lucas, (1843) 

 states that he himself, had been repeatedly bitten by the Malmigniatte 

 without any bad effects. Dr. Marx, in 1890, gave before the Ento- 

 mological Society of Washington, an account of a series of experiments 

 to determine whether the bite of Latrodectus mactans is poisonous or 

 not. He described the poison glands as remarkably small* and stated 

 that he had introduced the poison in various ways into guinea-pigs 

 and rabbits without obtaining any satisfactory results. Obviously, 

 carefully conducted experiments with the supposed venom were 

 needed and fortiuiately they have been carried out in the greatest 

 detail by Kobert (1901). 



This investigator pointed out that there were two factors which 

 might account for the discrepancies in the earlier experiments. In 

 the first place, the poison of spiders, as of snakes, might be so ex- 

 hausted after two or three bites that fiurther bites, following directly, 

 might be without visible effect. Secondly, the application of the 

 poison by means of the bite, is exceedingly inexact, since even after 

 the most careful selection of the point of application, the poison might 

 in one instance enter a little vein or lymph vessel, and in another case 

 fail to do so. Besides, there would always remain an incalculable and 

 very large amount externally, in the nonabsorptive epithelium. 

 While all of these factors enter into the question of the effect of the 

 bite in speciflc instances, they must be as nearly as possible obviated 

 in considering the question of whether the spiders really secrete a 

 venom harmful to man. 



*This is diametrically opposed to the findings of Bordas (1905) in the case 

 of the European Latrodectus ij-guttatus, whose glands are "much larger than 

 those of other spiders." From a considerable comparative study, we should also 

 imhesitatingly make this statement regarding the glands of our American species, 

 L. mactans. 



