'70 HANDBOOK OF PHYSIOLOGY. 



and clots on addition of fibrin ferment. The coagulable matter present 

 in greatest amount is B-fibrinogen, which clots on addition of lecithin, 

 or of lymph corpuscles, but not on the addition of fibrin ferment; A- 

 fibrinogen is separated from plasma by cooling, in minute regular rounded 

 granules, from which rounded distinctly biconcave discs arise, if watched 

 under the microscope, quite indistinguishable from colored blood-cor- 

 puscles; it is not coagulated by fibrin ferment. Finally, he considers 

 that when blood plasma dies, an action takes place between A- and B- 

 fibrinogen which are both compounds of proteid and lecithin. The es- 

 sential of this action is a loss of lecithin on the part of the former and 

 a gain of lecithin on the part of the latter, with the result of the pro- 

 duction of fibrin, a third proteid-lecithin compound, and the setting 

 free of other substances contained in the serum, including fibrin fer- 

 ment. Thus, fibrin ferment, a body which cm convert C-fibrinogen 

 into fibrin, is not present in living plasma, but is a result of its disor- 

 ganization or death. As the fibrinogen which can be clotted by the fer- 

 ment is only present in minimal amounts in living plasma, injection of 

 a solution of fibrin ferment or of shed blood does not produce intra- 

 vascular clotting, whereas injection of lymph corpuscles from lymphatic 

 glands or of lecithin, either of which will produce clotting of the other 

 fibrinogens which form the bulk of the coagulable matter in living 

 blood, leads to extensive intra-vascular clotting. 



The Blood Corpuscles. 



There are two principal forms of corpuscles, the red and the white, 

 or, as they are now frequently named, the colored and the colorless. 

 In the moist state, the red corpuscles form about 45 percent by weight of 

 the whole mass of the blood. The proportion of colorless corpuscles is 

 only as 1 to 500 or 600 of the colored. 



Red or Colored Corpuscles. Human red blood-corpuscles are 

 circular, biconcave discs with rounded edges, from -^Vo to :oW i ncn i n 

 diameter, and T? or i ncn i n thickness, becoming flat or convex on addi- 

 tion of water. When viewed singly, they appear of a pale yellowish 

 tinge; the deep red color which they give to the blood being observable 

 in them only when they are seen en masse. They are composed of a 

 colorless, structureless, and transparent filmy framework or stroma, in- 

 filtrated in all parts by a red coloring matter termed licemoglobin. The 

 stroma is tough and elastic, so that, as the corpuscles circulate, they 

 admit of elongation and other changes of form, in adaptation to the ves- 

 sels, yet recover their natural shape as soon as they escape from com- 

 pression. 



The term cell, in the sense of a bag or sac, although sometimes ap- 

 plied, is inapplicable to the red blood-corpuscle; and it must be consid- 

 ered, if not solid throughout, yet as having no such variety of consis- 

 tence in different parts as to justify the notion of its being a membranous 

 sac with fluid contents. The stroma exists in all parts of its substance, 

 and the coloring matter uniformly pervades this, and is not merely sur- 



