THE BLOOD AND THE LYMPH. 711 



sulphuric acid renders the blood black-brown. The corpuscles become 

 pale, and although still retaining some color, are scarcely recognizable, 

 their contours running mutually together. On the addition of nitre or 

 water, which latter throws down a white precipitate, they again become 

 distinct as minute, dull-yellow, round corpuscles. After some hours' 

 action of the acid all is dissolved. Concentrated hydrochloric acid, 

 which colors the blood brown, and produces a white precipitate, con- 

 tracts most of the cells, which are gradually dissolved, and renders 

 many of them granular internally, also producing rents in some of them, 

 so that the contents escape, in the form of a pale streak, appearing like 

 a stalk to the corpuscle ; subsequently they become so faint in color as 

 to be scarcely perceptible, without the aid of some saline solution. 

 After some hours many are dissolved, though a few offer a longer re- 

 sistance. 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, potassa acts the most pow- 

 erfully. A solution containing 10 per cent, makes the blood black, arid 

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

 smaller. The same thing takes place with a solution containing 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 potassa arid one 

 part water does not attack the corpuscles, beyond making them very 

 small ; at the same time they remain spherical, orjagged and folded. The 

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

 red, and afterwards, a bright brown color. On the subsequent addition 

 of water, the blood-corpuscles enlarge, as in no other reagent, to a size 

 of 0-006 of a line, remaining for the most part flat, and are then dis- 

 solved as in a dilute solution. Caustic soda, and caustic ammonia, in 

 solutions containing about 10 per cent., act like the corresponding 

 potassa-solution, only that the action is a little weaker, whilst concen- 

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

 potassa. 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 ma- 

 terials, chiefly water, from the cells, as it is always concentrated solu- 

 tions which so act. In these cases, also, since the blood-globules reflect 

 the light from more numerous points, the color 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, 

 0-001-0-002 of a line in size, or jagged, stellate bodies, or, lastly. 



