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 (1889), who discussed 
a number 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 fortunately they have been carried out in the greatest 
detail by Robert (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 further 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 specific 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 
unhesitatingly make this statement regarding the glands of our American species, 
L. mactans. 
