114 CIRCULATING FLUIDS: 



to those already described were perceived. Moist nuclei dis- 

 solved readily in caustic potash ; if the solution be supersatu- 

 rated with concentrated acetic acid, and heated, an imperfect 

 solution of the matter, precipitated by the acid, occurs ; a very 

 small quantity of dilute hydrochloric acid will, however, readily 

 dissolve the whole. On treating the filtered solution with 

 tannin, a copious precipitate was thrown down; ferrocyanide 

 of potassium caused a mere turbidity, or very sHght deposit. 

 Similar observations were made on the nuclei of carp's blood, 

 but the ferrocyanide of potassium caused less turbidity than in 

 the former case. The nuclei of human blood are scarcely dis- 

 cernible in the viscid sediment. The effect of reagents was 

 much the same as in the former cases. 



Hence we are led to infer that the blood-corpuscles are 

 chiefly formed of a substance closely related to the protein- 

 compounds, although not identical with any of them : possibly 

 the nuclei may be converted into fibrin, soluble in the liquor 

 sanguinis, after the metamorphosis of the blood-corpuscles has 

 been accomplished. On heating the nuclei on platina foil, a 

 fatty smell is first observed, and then an odour resembling that 

 of burning albumen. Upon heating them in a test-tube, and 

 applying litmus paper, the red colour is soon changed to a 

 strongly-marked blue. The ash has a reddish appearance, and 

 consists of peroxide of iron, lime, and phosphoric acid. 



D. The general chemical relations of the plasma (Jiquor 



sanguinis) . 



The plasma of living blood exists as a clear fluid, in which 

 the corpuscles are seen to float. If the blood has been 

 removed for some time from the body, the fibrin separates 

 from the plasma. This separation appears to take place simul- 

 taneously and uniformly throughout the whole of the blood. 

 As the fibrin contracts, it entangles the corpuscles ; the subse- 

 quent contraction tends to expel the serum, and thus the clot 

 is produced. The clot, at first soft and gelatinous, becomes 

 gradually more consistent, and idtimately appears as a mass, 

 capable of a certain degree of resistance, and floating in the 

 serum. 



There are certain pathological conditions, under which the 



