202 



fluids is that which may, with most propriety, be termed such, contains? 

 likewise, aqueous parts, which, while it remains in the bladder, the 

 lymphatics absorb and carry into the mass of the fluids. 



Of all the modern divisions, Fourcroy's is the best; Vicq-d'Azir ac- 

 knowledged its superiority over that proposed by Haller, in his Physiolo- 

 gy. Fourcroy admits six classes of fluids : 1st those which hold salts in 

 solution, as the sweat and urine ; he gives the name saline to such fluids : 

 2nd, inflammable oily fluids, all possessing a certain degree of consistence 

 and concrescjbility, as fat, and the cerumen of the ears, &c.; 3d. the sa- 

 ponaceous fluids, as the bile and milk; 4th, the mucous fluids, as those 

 which lubricate the internal coat of the intestinal canal ; 5th, the albu- 

 minous fluids, among which one may rank the serum of the blood ; 6th, 

 thefibrinous fluids, containing fibrina, as the fluid lust mentioned*. 



In proportion as we advance in our knowledge of animal chemistry, 

 the defects of these divisions become more, and more evident. In short, 

 the animal fluids are so compound, that there is not one which does not, 

 at once, belong to several of these classes, arid whose prevailing element 

 is not sometimes exceeded in quantity, by materials which commonly 

 form but a small part of them. 



LXXXIX The blood is the reservoir and the common source of the 

 fluids; these do not exist in the blood, with the qualities which character- 

 ize them, unless, after having been previously formed by the secretory 

 organs, they have been absorbed by the lymphatics, and conveyed, with 

 the chyle and lymph, into the circulatory system. Let us briefly attend 

 to its nature, although this belongs more especially to the department of 

 chemistry. The blood is red in man, and in all warm-blooded animals, 

 and even in some whose temperature is not very different frem that of the 

 atmosphere, as in fishes and reptiles. This colour, of a deeper or lighter 

 shade, according as the blood is drawn from an artery or a vein, varies 

 in its degree of intensity, according to the state of health or weakness. 

 It is of a deep red in strong and active persons, pale and colourless in 

 dropsical patients, and whenever the health is weak. By its colour 

 one may judge of all its other qualities. Its viscidity is greater, its sa- 

 line taste more marked, its peculiar smell stronger, when its colour is 

 deep. This colour is produced by a prodigious number of globular mo- 

 lecules, which move and float in an aqueous and very liquid fluid. When 

 the blood is pale, the number of these molecules diminishes, they seem 

 to be dissolved in cachexiae. 



The microscope, which affords the only method of perceiving them, 

 does not enable one to determine their bulk and their figure. Leeu- 

 wenhoek, who brought forward the idea of their being so minute, by his 

 calculation that they were one millionth part of an inch in size, thought 

 them spherical. Hew son says they are annular, and have an opening 

 in their centre. Others compare them to a flattened lentil, with a dark 



* BERZELIUS distinguishes the fluids formed from the blood into secretions properly 

 so called, and excretions, or those which are directly discharged from tiie body The 

 former class of fluids is destined to perform a farther office in the animal economy- 

 all of these are alcaline ; they are the bile, the saliva, and the fluid which is secreted 

 on the mucous and serous surfaces. In the latter division, acids predominate, the ex- 

 cretory fluids embrace the urine, the cutaneous and pulmonary transpiration, and the 

 milk. MAGKXDIE divides the secretions into exhalations, folUcular secretions, and glandu^ 

 far secretions. See APPENDIX, Note A A, for farther observations on this subject, 

 Copland. 



