.CHAP. II.] THE BLOOD. 121 



corpora lutea of the cow, is not identical with bilirubin. Salkowski 1 , 

 on the other hand, found haematoidin prepared from the con- 

 tents of a strumous cyst to be identical in all respects with 

 bilirubin. Preyer 2 , relying mainly though not entirely upon the 

 spectra of the two bodies, denies the identity. According to this 

 observer bilirubin possesses no definite absorption-band, whilst solu- 

 tions of haematoidin when examined with the aid of magnesium light 

 present a well-marked absorption-band between b and F, and a 

 weaker one nearly midway between F and G. 



The majority of physiological chemists are, however, now of the 

 opinion that haematoidin and bilirubin are identical. This matter will 

 be again referred to under 'bilirubin.' 



THE MINERAL CONSTITUENTS OF THE RED CORPUSCLES. 



It was pointed out in discussing the salts of the serum and plasma 

 that our information in reference to these was far from complete, in 

 consequence of the inherent difficulties which attach to the methods of 

 research. The same remark appears with still greater force to the 

 mineral matters of the corpuscles. It is possible to obtain plasma and 

 serum free from corpuscles (though certainly not free from all constitu- 

 ents of corpuscles, e.g. serum-globulin), but far from possible to obtain 

 corpuscles free from the liquids in which they float. Comparative 

 analyses, however, of the mineral matters of the serum and of the clot, 

 and of the blood as a whole, do lead to certain results which are to 

 be relied upon. They at once reveal, for instance, that the iron of 

 the blood is, with the exception of the minutest traces, contained in 

 the corpuscles, where we know it to exist as an essential constituent 

 of haemoglobin ; that the corpuscles are much richer in potassium 

 salts than the serum, and that the amount of chlorine is very much 

 greater in the latter than in the former. When, however, we enquire 

 whether phosphates and sulphates exist in the blood-corpuscles, or 

 whether these ingredients of the ash are not due to the oxidation of 

 organic constituents, we can merely say that the experimental data for 

 furnishing an answer to the question fail, though from the fact that 

 the blood-corpuscles are rich in lecithin we cannot doubt that nearly 

 the whole, if not the whole, of the phosphoric acid found in the ash, 

 is derived from the oxidation of that body. 



The ana- In order to impress upon the reader the difference between 



lysesof tne m i nera i constituents of the blood-corpuscles and the 



plasma, the results of C. Schmidt's analyses of both are 

 here appended : 



1 Salkowski, " Zur Frage iiber die Identitat des Hamatoidin und Bilirubin," 

 Hoppe-Seyler's Med. Chem. Untersuchungen, in. p. 436. 



2 Preyer, Die Blutkrystalle, p. 187. 



