710 SPECIAL HISTOLOGY. 



have in some measure been of very trifling importance ; and I, there- 

 fore, here adduce, chiefly from my own researches on the suhject of the 

 human blood-corpuscles, only what may serve to illustrate their anato- 

 mical and physiological relations. Water at first renders the blood- 

 globules spherical, and, owing to the diminution of the broad diameter, 

 consequent upon the increased thickness, smaller (from 0-002-0-0024 

 of a line), which may be best seen in corpuscles arranged in columns. 

 The size then usually remains without further change, and the coloring 

 matter and remainder of the contents slowly (sometimes suddenly, and 

 by fits and starts) escape, so that the fluid becomes dark-red, the cor- 

 puscles at the same time losing their color, and acquiring the aspect of 

 colorless vesicles or rings, so faint, that it is often difficult to perceive 

 them. But by the addition of tincture of iodine, which colors them 

 yellow, or of salts (common salt, nitre, &c.), of gallic or chromic acid, 

 which cause them to shrink, and to present a more defined outline, they 

 may be readily brought into view ; and it is thus satisfactorily shown 

 that water, by no means dissolves, or destroys them. Some blood- 

 globules always withstand the influence of the water for a longer time, 

 and are still colored when all the rest have lost their coloring matter ; 

 but it is not yet' ascertained, whether these are to be regarded as of 

 younger formation, as is commonly supposed, or of older. The latter 

 notion seems to be favored by the circumstance that older cells usually 

 have firmer membranes than younger ones, and also that blood-corpus- 

 cles, left to their fate out of the circulation for instance in extra- 

 vasated blood always, in time, become more resistant; but it must be 

 allowed that, at present, no decisive opinion can be given either way. 

 Many other substances act in the same manner as water, only more 

 powerfully and even destructively, particularly acids and alkalies; 

 although not all with equal energy. Gallic and pyroligneous acids, 

 aqueous solutions of chlorine and iodine, sulphuric ether and chloro- 

 form, act very much in the same way as water. In the first three the 

 blood-globules remain as distinct, pale rings, whilst in sulphuric ether 

 they are instantaneously transformed into the most delicate and exces- 

 sively faint rings, j J the original size, and which it is very difficult to 

 perceive in the finely granular coagulum that is formed at the same 

 time, although they are rendered more distinct by the addition of salts 

 (nitre for instance). I have seen no evidence of an actual solution of 

 the cells. Chloroform acts in the same manner, only more slowly, and 

 the corpuscles first become considerably smaller, and of a glistening 

 yellow color. Acetic acid, of 10$, at once renders the corpuscles ex- 

 tremely faint, so as to be scarcely perceptible, but they are by no means 

 dissolved, being visible, even at the end of several hours, in the form of 

 delicate rings. A solution, containing 20 per cent, of acid, acts more 

 energetically, and in glacial acetic acid, the cells are completely dis- 

 solved in the space of two hours, in the slimy brown blood. Concentrated 



