548 LECTURE XXIII. 



deep significance, namely, that of the origin of fibrinogen. This is something 

 of which we have no positive information. Apparently the liver plays an 

 important part in its production. P. Nolf * found that after extirpation 

 of the liver the fibrinogen content of the blood decreased rapidly. Experi- 

 ments performed by M. Doyon, A. Morel, and N. Kareff 2 point in the same 

 direction. They showed that after sub-acute poisoning of dogs with phos- 

 phorus oil, which causes a fatty degeneration of the liver, there is a decrease 

 in the fibrinogen content of the blood plasma, which lessens the coagula- 

 tion power of the blood. With a cock it was not found possible to cause 

 a fatty degeneration of the liver by phosphorus poisoning, and it was 

 likewise impossible in this case to cause fibrinogen to disappear from the 

 plasma. It is entirely impossible to draw binding conclusions from these 

 experiments, for both the extirpation of the liver and poisoning by 

 phosphorus are attacks whose effect upon the action of the whole 

 organism cannot be disregarded. It is possible that the liver not only 

 influences the production of fibrinogen, but other phases of the coagulation 

 process as well. We shall expect further experiments in this direction. 



In the coagulation process we have become acquainted with a very 

 essential property of the blood. We shall now turn to the individual con- 

 stituents of defibrinated blood, the serum and blood-corpuscles. The 

 former consists chiefly of two different albuminous substances, a globulin 

 and an albumin. We shall not stop here to discuss the unedifying question 

 as to whether these proteins are simple substances or not. This cannot be 

 decided in the light of our present knowledge, and even if it is possible by 

 fractional precipitation, or by "salting out," to effect- a separation into 

 simpler constituents, but little gain is made in our knowledge of these two 

 proteins, for even these fractions cannot be characterized, by the means 

 now at hand, nor upon the present basis of protein chemistry, as simple 

 substances. Besides these proteins, we find varying amounts of fat in 

 blood-serum. After a meal rich in fat, the amount present in the serum 

 may become so large as to give it a milky appearance. Serum invariably 

 contains cholesterol and lecithin, and in fact the former is, as we have 

 already stated, largely present in the form of fatty-acid esters. A sugar, 

 d-glucose, is also present in serum. The amount of the latter varies, but 

 only within narrow limits. 



We have already seen that the blood, besides providing nourishment, 

 also serves to carry the end-products of metabolism away from the cells. 

 For this reason we constantly meet with such products in the blood. It 

 is certain that they belong for the most part to the plasma, or its serum. 

 Their presence remained for a long time undiscovered, because from 

 moment to moment but small amounts of such substances are present. 



1 Bull. Acad. roy. Belgique, 1905, 81. 



2 Compt. rend. 140, 800 (1905). 



