244 THE BLOOD 



blood-clot (placenta sanguinis). If the blood is beaten during coagula- 

 tion, the fibrin separates in elastic threads or fibrous masses, and the 

 dcfibrinated blood which separates is sometimes called cruor, 1 and con- 

 sists of blood-corpuscles and blood-serum, while uncoagulated blood 

 consists of blood-corpuscles and blood-plasma. The essential chemical 

 difference between blood-serum and blood-plasma is that the blood- 

 serum does not contain even traces of the mother-substance of fibrin, 

 the fibrinogen, which exists in the blood-plasma, while the serum is pro- 

 portionally richer in another body, the fibrin ferment (see below). 



I. BLOOD-PLASMA AND BLOOD-SERUM. 

 The Blood-plasma. 



In the coagulation of the blood a chemical transformation takes 

 place in the plasma. A part of the proteins separates as insoluble fibrin. 

 The albuminous bodies of the plasma must therefore be first described. 

 They are, as far as we know at present, fibrinogen, nudeoprolein, ser- 

 globulins, and ser albumins. 



Fibrinogen occurs in blood-plasma, chyle, lymph, certain transudates 

 and exudates, in bone-marrow (P. MULLER), and perhaps also in other 

 lymphoid organs. The seats of formation of fibrinogen are, according 

 to MATHEWS, the leucocytes, especially of the intestine, according to 

 MULLER, 'the bone-marrow arid probably other lymphoid organs such 

 as the spleen and lymph glands, and according to Do YON and NOLF, 

 the liver. The statement that the intestinal wall is a seat of formation 

 of fibrinogen, a view that had already been held by DASTRE, is substan- 

 tiated not only by the direct researches of MATHEWS, but also by the 

 older and substantiated opinion that the blood from the mesentery vein is 

 richer in fibrinogen than the arterial blood. This origin, of fibrinogen has 

 been shown to be improbable by the recent .researches of DOYON, CL. GAU- 

 TIER and MOREL. The occurrence of fibrinogen in the bone-marrow and 

 other lymphoid organs as shown by MULLER, and an increase of fibrinogen 

 in the blood as well as in the bone-marrow of animals immunized with 

 certain bacteria, especially 'pus-staphylococci, indicates the formation 

 of fibrinogen in this tissue. The relation between the quantity of fibrin 

 and leucocytosis as shown by many investigators such as LANGSTEIN 

 and MAYER, MORAWITZ and REHN, also indicate such a formation of 

 fibrinogen. That the liver takes part in the formation of fibrinogen 

 is implied by the fact that the quantity of fibrinogen in the blood 



1 The name cruor is used in different senses. We sometimes mean thereby only 

 the blood when coagulated in a red solid mass, in other cases the blood-clot after the 

 separation of the serum, and again the sediment consisting of red blood-corpuscles 

 which is obtained from defibrinated blood by means of centrifugal force or by letting 

 it stand. 



