334 SPECIAL HISTOLOGY. 



the aid of some saline solution. After some hours many are 

 dissolved, though a few offer a longer resistance. Nitric acid, 

 when concentrated, renders the blood olive-brown, and the 

 corpuscles greenish. The latter are corrugated, but are not 

 rendered smaller, and are partly enclosed in the coagulum, 

 which is formed at the same time, in part free, and lying 

 above it. After several hours there is still no indication of a 

 solution going on, but this takes place at the end of a day. 

 Of the alkalies, potass acts the most powerfully. A solution 

 containing 10 per cent, makes the blood black, and at once 

 dissolves all the blood-cells," first rendering them spherical and 

 smaller. The same thing takes place with a solution con- 

 taining 20 per cent, of the alkali, except that some of the cells 

 remain for a time as pale rings, whilst a concentrated solution 

 of two parts potass and one part water does not attack the 

 corpuscles, beyond making them very small; at the same time 

 they remain spherical, or jagged and folded. The whole blood 

 is coagulated by this solution, and acquires, at first, a brick- 

 red, and afterwards, a bright brown colour. On the subse- 

 quent addition of water, the blood-corpuscles enlarge, as in no 

 other reagent, to a size of 0'006'", remaining for the most 

 part flat, and are then dissolved as in a dilute solution. 

 Caustic soda, and caustic ammonia, in solutions containing 

 about 10 per cent., act like the corresponding potass-solution, 

 only that the action is a little weaker, whilst concentrated 

 caustic soda (1J part to 1 part water) acts precisely like caustic 

 potass. The same phenomenon of a diminution of the blood- 

 cells, as that caused by some of the reagents above noticed, is 

 manifested also in many other instances, and may be referred 

 to the abstraction of materials, chiefly water, from the cells, 

 as it is always concentrated solutions which so act. In these 

 cases, also, since the blood-globules reflect the light from more 

 numerous points, the colour of the blood becomes brighter, 

 usually of a brick-red. Even the mere concentration of the 

 blood-plasma, by evaporation, causes the cells to shrink more 

 or less, in consequence of which they become either round, 

 dark, brilliant globules, 0*001 — , 002' // in size, or jagged, stel- 

 late bodies, or, lastly, diversely bent and plicated discs. All 

 concentrated solutions of metallic and other salts, act in the 

 same way, unless, like nitrate of silver, they exert an imme- 



