324 THE BLOOD. 



Of albumins proper, there are said to be present in the leucocytes 

 the so-called cell-globulins, of which Halliburton recognizes two 

 one coagulating at 50 C., the other at 73 C. and one of which 

 is by some thought to be identical with the fibrin ferment ; then 

 serum-albumin, and a mucinous body, the so-called hyalin sub- 

 stance of Rovida. These bodies, however, represent only a very 

 small portion of the solids of the leucocytes, as is seen from Lilien- 

 feld's 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 nucleo-albumin, which may be identical with the 

 nucleohiston, which has just been described. According to Lilien- 

 feld, indeed the plaques must be regarded as nuclear derivatives, and 

 he has accordingly termed them the nuclein platelets of the blood. 



The Coagulation of the Blood. 



According to modern ideas, the coagulation of the blood is ref- 

 erable in the first instance to the decomposition of fibrinogen 

 into fibrin and fibrinoglobulin. This decomposition, is thought 

 to be effected through the activity of a special ferment, the 

 fibrin ferment, which is supposedly contained in the cellular ele- 

 ments of the blood in the form of a pro-enzyme, and is set free 

 during the death of these elements as a calcium compound of 

 the pro-enzyme. According to Pekelharing, the ferment then trans- 

 fers its calcium to the fibrinogen, which is thus decomposed, and 

 is itself reconverted into the pro-enzyme, and as such imme- 

 diately combines with calcium, which is again transferred to an- 

 other portion of fibrinogen, and so on. This theory is in all like- 

 lihood correct in its general features, but has probably not yet 

 assumed its ultimate form. That other substances, besides fibrin- 

 ogen, a small amount of a neutral and a soluble calcium salt, and 

 the fibrin ferment, need not be present to effect coagulation, is cer- 

 tainly beyond dispute. But, on the other hand, we must admit that 

 our knowledge of the fibrin ferment itself and the mode of action 

 of the calcium salt is still imperfect. According to Halliburton, the 

 fibrin ferment is a cell-globulin and is contained as such in the 

 bodies of the leucocytes. Pekelharing, on the other hand, regards 

 the ferment as a calcium compound of a nucleo-albumin. Lilienfeld, 



