General nature of venoms 85 Venomous serpents 87 Nature of serpent-venoms 88 Natural immunity towards serpent-venoms 90 Artificial immunity towards serpent venoms 91 Venoms of batrachians and saurians 92 Fish-poisons 95 Poisons of the hymenoptera 96 Poisons of scorpions 97 Poisonous blood and serums 98 Poisonous meats 100 TOXINS AND VENOMS. PART I. _GENERALITIES REGARDING TOXINS AND ANTITOXINS._ CHAPTER I. ALKALOIDAL TOXINS, PTOMAINES AND LEUCOMAINES. =Alkaloidal Products of Cellular Life.= Before entering upon the study of the true toxins, which are products of an alkaloidal nature and of unknown composition, it is necessary to say a few words regarding the most definite of the toxic alkaloidal principles that are frequently encountered under various conditions, conjointly with the true toxins, particularly in venoms, and which, furthermore, are closely allied to these albuminoid toxins. These principles are formed in essentially reducing media, whether it be within the body of the organism, and by the simple exercise of its normal function, in which case the principles bear the generic name _leucomaines_[1]; or whether due to the action of anaerobic microbes, when they are designated as ptomaines.[2] These basic principles, which are essentially the products of cellular secretion, are usually toxic, and sometimes even extremely so. [1] ARMAND GAUTIER: Sur les leucomaines, nouveaux alcaloides, dérivés de la transformation des substances protéiques des tissus vivants. _Bull. Soc. Chim._, 2e série, XLIII, p. 158. [2] ARMAND GAUTIER: "Communication sur les bases d'origine putréfactive." _Bull. Soc. Chim._ (2), XXXVII, p. 305. As we shall presently see, ptomaines are essentially products formed during putrefactive fermentation. The toxic properties of extracts from the cadaveric fluids have long been known. Already in 1838 Panum[3] had met with these products in snake venoms. Bergmann and Schmiedberg[4] in 1868 isolated from septic pus a toxic substance which they named _sepsin_; and almost at the same time Zuelzer and Sonnenschein[5] reported having isolated from anatomical preparations an alkaloid possessing mydriatic properties. It is, however, due particularly to the researches of Selmi and Armand Gautier that we are now so well informed regarding these toxic principles. [3] _Virchow Archiv._, X, p. 301. [4] _Medic. Centralblatt_, 1868, p. 497. [5] _Berlin. Klin. Woch._, 1869, No. 2. The labors of Armand Gautier were first published in his _Traité de Chimie Appliquée à la Physiologie_; those of Selmi in the _Actes de l'Académie de Bologne_.