SUICIDE OF SCORPIONS. 
31 
opinion that a gradual innoculation of cobra poison would 
produce an immunity from its elfects, and states that Dr. 
Shortt has tried the experiment with a dog with little 
success, but the experiment was irregularly carried out and 
needs careful repetition. There is here, I believe, a probable 
explanation. The cells of the poison gland secrete the poison 
from the blood, i.e., they build up the poison from the nutri- 
tive matter furnished by the blood. Some of this poison may 
become absorbed into the blood, and there are possibly, 
always, small quantities of the poison in the blood, thus 
a constant but very gradual innoculation is taking place, 
resulting in complete immunity. Professor Ray Lankester 
has recently suggested this to me in a letter, and has 
further pointed out that we have here something similar 
to the immunity of Pasteur's dogs from hydrophobia. 
I have endeavoured to discover minimal amounts of 
poison in the scorpion's blood by injecting it into insects, but 
am unable to produce any effect. It wiU be interesting to 
try this with the much more virulent poison of the cobra, but 
this and other experiments I have been obliged to defer for 
the present. I may add here that I shall be exceedingly 
obliged to any one who will send me any observations upon 
the habits of the scorpions, or Kving specimens of the 
various kinds of scorpions in any district, more expecially 
the so-called water scorpion which I am particularly anxious 
to procure. 
