SECRETION. 259 



is mixed with the uric acid. Urine seems to contain only a single 

 peculiar characteristic matter ; but milk has as many as three, 

 viz. butter, curd, and sugar of milk, which, however, seem to be 

 produced by different organs that mingle their fluids in the same 

 receptacle. The perspired fluid appears to have no peculiar 

 matter, but to be a very watery liquid, with hardly a vestige of 

 the albumen of the blood, and, in short, is the same as the other 

 excretory fluids would be when deprived of their peculiar matter. 

 If we suppose this matter taken away from those excretions which 

 possess it, the remaining fluid will be found to have properties 

 very different from the fluid part of the secretions, when equally 

 freed from their peculiar matter. That of the excretions is acid, 

 contains earthy phosphates, and when evaporated, leaves a much 

 larger residue than the fluid of the secretions. This residue is 

 yellowish brown, of the consistence of syrup, with an unpleasant, 

 sharp, saline taste of the salt that it contains. It reddens litmus, 

 is most soluble in alcohol, and this spirituous solution contains the 

 muriates of the blood, together with free lactic acid, much lactate 

 of soda (the soda being the free alkali of the blood, neutralised 

 by this acid), and the extractive matter, which always accom- 

 panies this neutral salt. The part insoluble in alcohol contains a 

 distinguishable quantity of phosphate of soda, a little of a similar 

 animal matter to that found in the secretions, and also the earthy 

 phosphates which were held in solution by the lactic acid, and 

 were precipitated by the action of the alcohol. The urine pos- 

 sesses also a number of other substances, which will be specified 

 when describing this secretion in particular."* 1 



The most simple mode of secretion is where the ordinary arteries 

 in the neighbourhood ramify on a surface, as on the skin, mucous 

 or serous membranes, and the fluid is poured forth upon it. The 

 next mode is where the arteries ramify on the inner surface of 

 a cup, called a cell or crypt, into which the fluid is poured, and 

 in which it remains a longer or shorter time and becomes 

 more consistent. The next is where this cup is so lengthened 

 that it becomes a pouch or follicle. If prolonged still more, 

 it is a canal, of various lengths. Next, what is termed a gland, 

 is but a conglomeration of numerous canals, beginning each 

 from a blind extremity and uniting together till they form one 

 tube only, which opens upon some surface under the name of 



d General Views of the Composition of Animal Fluids, by J. Berzelius, M.D- 

 Medico- Chirurgic. Trans, vol. Hi. p. 234. 



s 4 



