120 FOURTH REPORT — 1834. 



experiment, the affinity excited is between chlorine and animal 

 matter, not iron and chlorine. And if the mineral acids have 

 not the same effect, this does not prove the iron to be in a me- 

 tallic state ; for if it were so, and unprotected by the animal 

 matter, it would be oxidized, and then dissolved by the acid. 



The labours of chemists to explain the mode in which the 

 elementary substances are united to produce the colour of the 

 cruor, however they may be unsatisfactory in this respect, have 

 thrown much light upon the reactions of these substances. Such 

 expei'iments, on the other hand, have introduced as constituents 

 of the blood, products which are perhaps merely the effects of 

 the chemical operations ; or new combinations, not existing in 

 nature, of its elements. The iron seems to enter in too small a 

 quantity to form a metallic pigment for the cruor. Whatever 

 changes the constitution of the blood, as a living product, also 

 changes its colour. " Since its chemical composition is only a 

 product of life, so are we unable by any aids derived from inoi'- 

 ganic nature to produce it. The colour has its cause in the con- 

 stitution of the blood as an organic whole ; and each of its ele- 

 ments, iron amongst the rest, contributing to that constitution, 

 enters into the production of its colour*." 



T/ie Lymph, or liquor sanguhds. — The clear fluid in which 

 the cruor, or mass of corpuscles, is diffused. It separates spon- 

 taneously into two portions, fibrin and serum. 



Fibrin. — I refer to Berzelius for all that is yet known con- 

 cerning this substance. Since Miiller's discovery, it is distin- 

 guished fi'om the corpuscles; and De Blainville and Hodgkin 

 have shown that its fibres do not consist of strings of minute 

 globules. 



Serum. — Lecanu has repeated the analysis of serum, and as- 

 serts, that certain oily substances exist as components, which 

 were unnoticed by Berzelius and Marcet. His mode was, after 

 desiccating a known quantity by moderate heat, and thus deter- 

 mining the quantity of water, to treat successively, with boiling 

 water and boiling alcohol at 40°, the residue of desiccation. The 

 Avater dissolved the soluble salts and extractive matters, the al- 

 cohol the fat matters. The watery solution was evaporated ; the 

 residue treated with alcohol to separate the extractive matters 

 soluble in it. What was insoluble was calcined, to determine the 

 proportion of organic matter it still contained ; the residue again 

 treated with boiling alcohol to separate the hydrochlorates. 



The fatty matters taken up by the boiling alcohol were sepa- 

 rated from each other by means of alcohol at 33°, which does 

 not dissolve when cold the crystallizable fat, but does the oily. 



* Burdach, iv. 85, 



