These autointoxications are controlled by the nervous system, and the latter alone is the cause of a larger number of maladies than is generally believed; in fact, if the mechanism of nutrition be reduced to its most simple elements, it will be seen to consist of the penetration of the foods, of the plasmatic principles, to the cells; of their transformation within the interior of the cells, and finally the rejection of all the matter that could not be utilized. It is the nervous system that commands or dominates this mechanism, that controls the taking-up of assimilable elements and the elimination of toxic principles, the fruit of assimilation or disassimilation, and in such a manner, in fact, that this same nervous system can, at its will, cause starvation, or intoxicate. The marvelous cures obtained by magnetic methods are due to no other causes than favorable changes in the nervous system. =General Mode of Action.=--The toxins, of whatever kind, always behave like diastases, in the sense that their definite action appears to be absolutely independent of their mass, and that imponderable quantities suffice to cause serious morbid affections and profound modifications in nutrition. Koch has shown that tuberculin is capable of affecting 60 trillion times its weight of the living human being. According to Vaillard one milligramme of tetanus toxin will kill a horse weighing 600 kilos. These two examples show what an enormous power the toxins possess. My views regarding the manner in which diastases act I have developed at length in my work _Nature des Diastases_. The close analogy between these substances and the toxins, an analogy upon which, moreover, I have dwelt at some length, permits me to refer the reader who is desirous of fuller details to the small work just mentioned. The mode of action of diastases resembles singularly closely that of the catalytic substances, and we will admit, for the moment, that they act by intermediary combination, resulting in their rapid decomposition. We owe to Ehrlich[31] a new conception relative to the nature and mode of action of the diastases, and which to-day plays an important rôle in all our conceptions regarding immunity.[32] [31] EHRLICH: _Klinisches Jahrbuch_, 1897, VI. _Proceedings of the Royal Society_, 1900, No. 482, p. 424. _Nothnagles' specielle Pathologie und Therapie_, 1901, VIII, Schlussbetrachtungen, p. 163. [32] To have a complete exposé regarding this question, it will be profitable to consult No. 4 of this collection on _Sérums Immunisants_.