524 CHEMISTRY OF BLOOD-CORPUSCLES. [sect. 221. 



importance. I shall, therefore, only adduce here, principally from investi- 

 gations of my own on the blood-globules of man, what may be of use in 

 settling their anatomical and physiological characters. Water renders the 

 blood-globules first spherical, and, owing to the decrease of the horizontal 

 diameter which accompanies increase in thickness, they appear to become 

 smaller (0-002'" to 0-0024'"), as may be best observed on corpuscles which have 

 united to form rouleaux. Then, generally without any further alteration in 

 size, the colouring matter and other contents are extracted, sometimes slowly, 

 sometimes suddenly by a jerking swelling up of the corpuscles ; in this manner 

 the fluid portion of the blood becomes coloured, the corpuscles, on the other 

 hand, appearing as colourless vesicles or rings, so faint, that it is often difficult 

 to detect them. Yet by the addition of tincture of iodine which colours them 

 yellow, or of the reagents which render them smaller, and make their outline 

 more distinct, such as gallic or chromic acid, and various salts (chloride of 

 sodium, nitrate of potass, etc., they can readily and distinctly be brought 

 into view, and thus it may be shown that water by no means dissolves or 

 destroys them. Acetic acid of 10 per cent, renders the corpuscles extremely 

 pale instantaneously, so that they are scarcely any longer perceptible ; but 

 still they are not dissolved, for they may be seen several hours afterwards as 

 delicate rings. A solution of 20 per cent, acts more energetically, and in 

 glacial acetic acid, the cells are found after two hours to be quite dissolved 

 in the greasy brown mass into which the blood is converted by this re-agent. 

 Of all the alkalies, potass acts the most powerfully. A solution of 10 per cent, 

 renders the blood black, and immediately dissolves all the blood-cells, render- 

 ing them first spherical and smaller. A solution of 20 per cent, acts in a 

 similar manner, except that a few cells remain behind for some time as pale 

 rings ; while, on the other hand, a concentrated solution of two parts potass 

 to one part water, does not attack the corpuscles beyond rendering them 

 extremely small, and then they either remain spherical or become jagged and 

 folded. The blood, as a whole, is coagulated by .this solution, and becomes of 

 a brick-red colour, passing on to a bright brownish-red. On the subsequent 

 addition of water, the blood-globules enlarge to o - oo6'", but otherwise appear 

 as if no re-agent had been added, generally remaining flat ; they then disap- 

 pear as in an ordinary dilute solution of potass. The same phenomenon of 

 diminution in size of the blood-cells, which is produced by some of the sub- 

 stances already mentioned, is of very common occurrence on the addition of 

 re-agents, and must be attributed to the abstraction of various substances, 

 especially water, from the blood-cells, seeing that it is always concentrated 

 solutions which act in this manner. In these cases also, from the blood- 

 globules reflecting the light at several points, the colour of the blood becomes 

 brighter, generally brick-red ; but the change in hue is not always to the 

 degree exactly corresponding to the shrinking of the cells {Moleschott). Even 

 simple concentration of the blood-plasma by evaporation, causes the blood- 

 cells to shrivel more or less, and then they are either converted into round 

 dark shining globules, 0*001 '" to 0*002'" in size, or into jagged stellate bodies ; 

 or, lastly, into variously-curved and folded plates. All concentrated solutions 

 of metallic and other salts act in the same manner, except in those instances, 

 by nitrate of silver, for example, where the corpuscles are immediately 

 destroyed. The hydro chlorates and nitrates of the alkalies act more strongly 

 than the sulphates and phosphates of the same degree of concentration. 



