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Proceedings of Royal Society of Edinburgh. [sess. 
graphically described, among others, by Hooker and Ball in their 
Journal of a Tour in Marocco and the Great Atlas^ hut only to 
he dismissed as impostures, rendered possible by the previous 
extraction of the poison-fangs, or by some other disabling 
operation. Although, possibly, the performances are at times, or 
even frequently, impostures, it almost appears as if this conclusion 
were arrived at more because of their improbability and their 
apparent defiance of knowledge regarding the effects of serpents’ 
venom, than because of satisfactory or sufficient proof having been 
obtained of the conclusion. Some of the facts which I shall bring 
before the Society will, on the other hand, show that this conclusion 
can no longer be justified on the ground that the asserted facts imply 
impossibilities. 
It may he instructive to associate with this belief in the posses- 
sion, under certain conditions, by human beings of a power success- 
fully to resist the poisonous effects of serpents’ venom, and with 
the evidences in its support, the further belief that venomous 
serpents are themselves protected against the effects of bites 
inflicted upon them by individuals both of their own and of other 
species. On mere anatomical grounds it is difficult to understand 
how serpents could escape the absorption of their own venom 
through mucous surfaces, even admitting that absorption of venom 
does not occur in normal conditions of these surfaces. Yeriom 
must, however, be so frequently introduced into their bodies, in 
situations where absorption could not fail to occur, by the bites in- 
flicted upon them by other serpents, that the conclusion seems 
inevitable that they possess some protective quality, without which, 
probably, no venomous serpents would now be in existence. Hot 
only have many general observations been made in support of this 
belief, but it has been proved to be correct by direct experiments, 
such as those made by Fontana of Tuscany more than a century 
ago, and by Guyon, Lagerda, AVaddell, Kaufmann, and Sir Joseph 
Fayrer. 
This, and other evidence, pointing to the existence of protection 
against venom, not only in serpents themselves, but also, in certain 
exceptional circumstances, in human beings, several years ago 
originated a wish to further investigate the matter. It was 
obviously suggested that if protection occurs, it must be caused by 
