Page:Physiological Researches upon Life and Death.djvu/28

Rh Hence it follows that the sanguineous is the mean system, the centre of organic life, as the brain is of animal life, where those particles to be assimilated, and those, which having already undergone assimilation, are destined to be thrown out, confusedly circulate; so that the blood is composed of two parts, the one recrementitious, produced by the aliments and the exhausted materials of nutrition, and the other excrementitious, which is the rubbage, the residuum of all our organs, and which supplies the secretions and external exhalations. These last functions, however, sometimes serve also to throw out certain digestive products, which have had no concurrence in nourishing the parts. This may be seen in the urine and sweat, after copious potations. The skin and kidneys are then excretory organs, not of nutrition but of digestion. This may be observed still more clearly in the production of milk, a fluid manifestly formed out of that portion of the blood, which has not been assimilated by the nutritive process.

There is not the same conformity between the two orders of functions of organic life, as between those of animal life; the enervation of the first does not necessarily bring on a diminution of the second: hence leanness, marasmus, &c. states of the body in which assimilation in part ceases, dis-assimilation is exercised uninterruptedly.

These grand differences between the two lives of the animal, and those not less strongly marked limits which separate the two orders of phenomena of which each is the assemblage, appear to me to offer to the physiologist, the only real division which can be established between the functions.

Artificial methods we shall leave to the other sciences; let us pursue the order of the phenomena, connect the ideas we form of them, and we shall then see, that the greater