416 OF NUTRITION. 



this precipitate is insoluble in the solution of nitre, and possesses the properties 

 of arterial fibrin.* Hence it may be inferred, that the Fibrin of Venous blood 

 most nearly resembles albumen ; whilst that of Arterial blood, and of the Buffy 

 coat, contains more oxygen, and is more highly animalized. It is evident, 

 from this circumstance, that the matter of the Red Corpuscles is by no means 

 the only constituent of the Blood, which undergoes a change in the respiratory 

 process ( 540) .t When decomposition commences in a coagulum of Fibrin 

 withdrawn from the body (and even in the greatly debilitated living body, in 

 which the fibrin appears to be imperfectly formed), a granular mode of Aggre- 

 gation is evident in the particles of the mass, thus showing its affinity to 

 Albumen, when its peculiar vital characters have departed, or are possessed 

 by it in an inferior degree. 



554. It appears to be in the Fibrin of the Blood that all the organized 

 constituents of the body have their immediate origin ; and it may hence be 

 designated as the plastic or organizable constituent of the nutritious fluid. 

 To use a rather homely illustration, Albumen, Fibrin, and Organized tissue, 

 stand in much the same relation to each other, with raw cotton, spun yarn, 

 and the woven fabric. That the particles of perfectly elaborated Fibrin are 

 capable, in solidifying, of spontaneously assuming a definite arrangement, 

 cannot now be questioned. In the ordinary Crassamentum of healthy Blood 

 ( 582), this arrangement can be seen, by examining thin slices under the 

 microscope ; especially after the clot has been hardened by boiling. A num- 

 ber of fibres, more or less distinct, may be seen to cross one another ; forming, 

 by their interlacement, a tolerably regular network, in the meshes of which the 

 red corpuscles are entangled-. This fact was known to Haller ; but it has 

 been generally overlooked by subsequent physiologists, until attention was 

 drawn to it by the inquiries of Messrs. Addison, Gulliver, and others. It is 



* Scherer, Chemisch-physiologische Untersuchungen ; Annalen der Chemie, Oct., 1841; 

 quoted in Graham's Chemistry, p. 1025. 



t It appears, from the recent inquiries of Mulder, that the Protein-base of Fibrin may 

 exist in different states of definite combination with Oxygen. When Fibrin is long 

 boiled, so that part of it is dissolved, the soluble portion is found to consist of Triioxide 

 of Protein,- whilst the insoluble residue is in the state of Deutoxf.de. When Albumen is 

 boiled for a sufficient length of time, a Tritoxide of Protein is formed and dissolved in 

 like manner; but the residue is simple Albumen. Tritoxide of Protein may be further 

 produced, by exposing Fibrin to Oxygen gas. It is found in small quantity in healthy 

 blood; its amount being greater in arterial than in venous: but it forms a much larger 

 proportion of the Buffy coat, of which 14 per cent, may be dissolved by a quarter of an 

 hour's boiling. This soluble matter has been mistaken for Gelatin ; but its composition 

 is altogether different; and it is slated by Mulder to agree exactly with that which Dumas 

 has analyzed as Fibrin. These Oxides of Protein are regarded by Mulder as formed at 

 the expense of the Fibrin during its passage through the Lungs; and as being the real 

 materials of the nutritive process ; and he denies that any other constituent of the blood 

 undergoes oxidation in the pulmonary capillaries. In this view he is probably as much 

 in error, as are those who deny that any element but the Red Corpuscles is concerned in 

 the respiratory process. How far he is correct in asserting, that the oxides of Protein 

 alone are the materials of the nutritive processes, further researches alone can deter- 

 mine. It appears to the Author, however, that the doctrine is inconsistent with known 

 facts in regard to the organizability of true Fibrin. And it may be remarked, that the 

 differences of opinion which prevail amongst the most eminent Chemists,on topics which 

 lie at the foundation of Physiological Chemistry, should lead us to hesitate before ad- 

 mitting the novelties continually put forth by one or other of them as the basis of our 

 deductions. To him it appears, that the direct observation of Vital phenomena, about 

 which there can be little or no difference of opinion, is a much surer basis for theorizing 

 than those Analyses of the Chemist in which the utmost delicacy of manipulation is 

 required to insure even tolerably accurate results, and as to the details of which, a new 

 set of statements is put forth from some of the great Continental Laboratories, almost 

 every month. For the detailed account of Mulder's researches, see the Annalen der 

 Chemie und Pharmacie, Band xlvii. 



