CHEMICAL EXAMINATION OF THE BLOOD. 343 



felcPs table, and it is doubtful indeed whether their true chemical 

 nature has been sufficiently established. 



The Plaques. 



Of the chemical composition of the plaques little is known. 

 According to Lilienfeld, they contain an albuminous substance and 

 a nuclein ; for on treatment with artificial gastric juice they can be 

 differentiated into a homogeneous portion, which is subsequently 

 dissolved, and an insoluble granular portion, which gives the vari- 

 ous reactions of the nucleins, and may be shown to contain phos- 

 phorus. In the plaques the albumin is probably combined with the 

 nuclein to form a nucleoproteid, which may be identical with the 

 nucleohiston just described. According to Lilienfeld, indeed the 

 plaques must be regarded as nuclear derivatives, and he has accord- 

 ingly termed them the nuclein platelets of the blood. 



The Red Corpuscles. 



The red corpuscles of the blood, as has been mentioned, owe their 

 color to the presence of haemoglobin or its oxygen compound, oxy- 

 hemoglobin. This may be extracted by diluting with water, by 

 alternate freezing and thawing, by shaking with ether, chloroform, 

 etc. The blood is thereby rendered lake-colored, and on microscopi- 

 cal examination it will be observed that instead of the original cor- 

 puscles, so-called blood-shadows are now found. These are colorless 

 ring-like bodies, and constitute the stroma of the red corpuscles. 

 In the circulating blood the dissolution of the hemoglobin is pre- 

 vented by the presence of large amounts of sodium chloride. Such 

 blood is said to be hyperisotonic i. e., it contains more sodium 

 chloride than is necessary to prevent the dissolution of the coloring- 

 matter from its corpuscles. Within the corpuscles the haemoglobin 

 is supposedly not present in the free state, but in combination with 

 some other substance, such as lecithin ; and Hoppe-Seyler accord- 

 ingly distinguishes between the so-called arterin and phlebin, which 

 represent the lecithin compound of oxy hemoglobin and haemoglobin 

 respectively. 



As has been mentioned, the red corpuscles represent nearly one- 

 half of the liquid blood. They contain about 57.7 per cent, of 

 water and 40.5 per cent, of oxy hemoglobin, while the constituents 

 of the stroma inclusive of mineral salts amount only to about 1.9 per 

 cent. Among these constituents Halliburton's cell-globulin is said 

 to be most abundant ; in addition we find traces of lecithin, choles- 

 terin, and nucleo-albumin, while serum-albumin and albumoses are 

 apparently absent. In the nucleated red corpuscles of birds we 

 further meet with the integral constituents of the nuclei, among 

 which nucleohiston probably prevails. Its basic constituent, histon, 

 was first discovered by Kossel in the red corpuscles of the goose. 



