Chyle, in animal economy, is that white fluid, produced from the nutritious part of the food, in the first passages, after the fibrous or feculent matter has been separated: it is chiefly generated in the milk-vessels of the mesentery, whence, it passes to the receptacle of the' chyle, situated under, the left kidney, and is conveyed to what is called the thoracic duct, or the canal of the chest, from which it enters certain veins, where it is mixed with the blood; in short, it is the only supply of that vital fluid, and hence the great importance of wholesome food, from which alone a salubrious blood can be prepared, will be easily conceived. In this-view only, we have introduced the word chyle: a liquor which resembles m:lk; has a sweetish-saline taste; easily coagulates; and consists of a mixture of oily, watery, and lymphatic parts (see Lymph) ; its milky colour arises from the com bination of oil with water ; an instance of which occurs in the milk of almonds.

As the chyle is, by Nature, intended to form the blood, to supply the body with nutritious juices for the daily loss and waste it sustains, it is obvious that this salutary process ought not to be interrupted by violent exercise after meals ; because the chyle is supposed not to be completely secreted, till about four hours after the food has been taken.

Dr. Darwin observes that, tho' the chyle, from different kinds of aliment, is very similar, and all the various constituent parts of animal bodies are ultimately produced from the chyle, by sanguification and secretion, yet it happens, that some kinds of aliment possess a greater quantity of these particles, than others : such materials, for instance, as already contain much sugar, mucilage, and oil, as the flesh of dead animals, or the fruits and seeds of vegetables.