POISON OF MOSQUITO-BITE LT 
@ poisonous saliva was introduced. He noticed that if the mosquito punctures 
the skin without entering a blood vessel, although it may insert its proboscis 
for nearly its full length, no poisonous effect is produced upon the skin, but 
when the proboscis strikes blood and the insect draws it, the subsequent swelling 
and poisonous effects are obvious. He argued that these effects indicate a con- 
stant outpouring of some sort of poisonous fluid during the blood-sucking 
process. 
Miall (1895) maintains that it can not positively be said whether poison is 
injected into the wound or not. His statement is, “‘ No poison gland has hitherto 
been demonstrated, and there is some reason to believe that the irritation of the 
wound is slight in cold weather and only becomes intense during great summer 
heat.” But in our chapter on the anatomy of mosquitoes we have shown that 
Maclosky has demonstrated a differentiation in the salivary glands, one of each 
set being modified to secrete the poison. Fritz Schaudinn is inclined to believe 
that the mosquito bite is poisonous not because of any poisonous secretion of the 
salivary glands, but because of toxins produced by plant parasites in its 
esophageal diverticula. 
The purpose of the mosquito poison has been the subject of some conjecture. 
The old Réaumur hypothesis, that it causes the blood to become more liquid and 
more readily sucked up by the mosquito, has had its adherents. Osten Sacken 
and Miall, however, believe that it is probable that the piercing mouth-parts of 
the mosquito were originally acquired for the purpose of sucking the juices of 
plants, and Maclosky advances the idea that the chief food of mosquitoes is not 
animal blood but the proteids of plants, and that probably the poison injected 
may prevent the coagulation of proteids and so promote the process of suction. 
Prof. John B. Smith was inclined to believe in the Réaumur hypothesis, that 
the poison prevents the clotting of the blood in the stomach of the mosquito. 
He says: 
“A mosquito bites, primarily to obtain food; there is neither malice nor 
venom in the intent, whatever there may be in the act. Theoretically there 
would seem to be no reason why there should be any pain from the introduction 
of the minute lancets of the insects, and the small amount of blood-letting is 
usually a benefit rather than otherwise. Unfortunately, however, in its normal 
condition the human blood is too much inclined to clot to be taken unchanged 
into the mosquito stomach; hence, when the insect bites, a minute droplet of 
poison is introduced, whose function it is to thin out the fluid and make it more 
suitable for mosquito digestion. It is this poison that sets up the inflammation 
and produces the irritation or swelling. If we make a puncture wound with a 
fine needle, a small droplet of blood will exude which will almost at once harden 
into a clot, and if we attempt a little later to break that clot, we will find it tough 
and hard to disintegrate. If we allow a mosquito to bite until it is fully gorged 
and then smash it, we find that the blood from the gorged abdomen is much 
more fluid and spreads out thin. If we further allow it to dry, there will be no 
clot ; but a thin spread of material which is brittle and breaks readily into frag- 
ments. 
“The pain is caused entirely by the action of the poison in breaking up the 
blood, and as the first act of a biting mosquito is to introduce this poison into 
the wound, the pain and inflammation will be the same, whether the insect gets 
