For this reason, in practice, but very little serum is usually necessary in order to augment the natural resistance of a man of average weight or of a large animal; it is sufficient in most cases to give an injection of 10 or 20 c.c. in order to cure human beings who have been bitten. The clinical proof of this is, moreover, to be found in the cases, already very numerous, that have been published in the course of the last few years in the scientific journals of all countries. I have gathered together a few of these in the concluding pages of this book, and I would beg the reader to be good enough to refer to them.
PART IV.
VENOMS IN THE ANIMAL SERIES.
CHAPTER XVI.
1.—INVERTEBRATES.
Besides reptiles, many other animals possess poison-glands and inoculatory organs which they employ, either to defend themselves against their natural enemies, or to capture the living prey upon which they feed.
The venoms that they produce are still, for the most part, but little understood. A few of them, however, have excited the curiosity of physiologists, especially those secreted by certain batrachians, such as the Toad, and certain fishes, such as the Weever. Some of them exhibit close affinity to snake-venom, and are composed, like the latter, of proteic substances modifiable by heat and precipitable by alcohol; others possess altogether special characters, and resemble alkaloids.
The lowest animal group in which these secretions begin to be clearly differentiated is that of the Coelenterates.
A.—Coelenterates.
It has been shown by Charles Richet[108] that the tentacles of sea-anemones (Anemone scultata) contain a toxic substance which has the carious property of causing intense itching, pruritus, and even urticaria. This poison is perfectly soluble in alcohol, and can be prepared in the following manner:—