It may be well to offer a critical examination of the foregoing cases.
If they are genuine effects of the poison of _Latrodectus mactans_,
they must afford a _recurrence of corresponding symptoms_. They may
differ in _degree_, because the quality of the venom may vary; first,
from the season in which the bite occurred (and judging from cases I, IV
and V, the poison of _Latrodectus mactans_ is most virulent in the month
of September), and, secondly, from the more thorough elaboration of the
venom. It is known that the poison of _Crotalus horridus_ differs in
intensity according to the frequency with which the snake has bitten in
a given period of time; of four successive "strikes" in four different
organisms, and at brief intervals, the intensity of the action will
vary, so that while the first wound is lethal the last is not--on which
fact depends the vaunted reputation of many an antidote to the bite of
the rattlesnake. That this may be also true of the spider poison is the
only explanation I can offer for the fact that many naturalists have
allowed themselves to be bitten by spiders of reputed poisonous species,
and with impunity.