Even in the normal condition, the urinary toxicity varies greatly; and this is easily conceived since the physiological phenomena that control this secretion undergo incessant rise and fall. Thus, for example, the urines eliminated during sleep are less active than those produced during waking, because during sleep the elimination of cellular poisons is at a minimum. Exercise, walking, physical and intellectual labor, exert their portion of influence on these oscillations of toxicity; and this variation of toxicity is due not to any one variation in the mineral extractive matters, but rather more or less to the organic toxic products. We will not dwell further on this subject, but will simply refer to the work by Charrin, already mentioned, for all supplementary details. =Autointoxications.=[80]--The cells of the organism having, as a whole, a life very much like that of the microbes, it is quite natural that among the excreted products of the living tissues there should be found the same substances formed as a result of the anaerobic fermentation of albuminoids. Experiment has demonstrated that this is so, and Armand Gautier has irrefutably proven the existence of these principles.[81] Bouchard was the first to demonstrate the toxic nature of muscle extract,[82] and Roger[83] established the fact that the toxicity of this extract is due to ferment-toxins; it has since been recognized that after death these toxins accumulate in the muscles. [80] CH. BOUCHARD: _Des Autointoxications_. Paris, 1887. [81] _Bull. Acad, de Médecine_ (2), X, p. 947, and XX, p. 115. [82] BOUCHARD: _Leçons sur les Autointoxications_, Paris, 1887. [83] ROGER: Toxicité des Extraits des Tissus Normaux. _Soc. de Biolog._, 1891, p. 728. The extract of kidney made rapidly by cold process by triturating the washed kidney with glycerin, and precipitating the glycerinic solution with alcohol, contains toxic ferments to which the name "_hystozymes_" has been given.[84] These ferments split up hippuric acid into benzoic acid and glycocoll. Lépine has likewise discovered in the kidney a very toxic pyrogenic substance.[85] Roger has given us evidence of the toxic properties of the liver, washed and pulped, and then sterilized by filtration through a porous diaphragm. This scientist has shown that the toxic properties are due to albuminoids, which lose their activity when heated to 100°C.[86] [84] It is well to recall here that the kidneys contain both reducing and oxidizing ferments, as has been demonstrated by de Rey-Pailhade, and later by Abelous and Gérard. [85] LÉPINE: _Compt. rend. de l'Acad. des Sciences_, May 13, 1889; _Soc. de Biol._, 1891, p. 724. [86] ROGER: _Compt. rend. Soc. Biol._, 1891, p. 727.