210 BLOOD. 



fatty acids in the serum (enclosed in the clot) may be rendered 

 insoluble by strong dilution with water. There are at all events, a 

 number of possible sources to which the fibrin-fat may and indeed 

 must in part be referred. It is only necessary therefore, for the 

 determination of this question, to ascertain whether this fibrin-fat 

 differs specifically from the fats associated with the other constituents 

 of the blood. Such, however, does not seem to be the case, for as 

 far as my own and Virchow's enquiries extend, the fibrin only 

 contains fats which belong to some one or other of the blood-con- 

 stituents. Virchow found a considerable quantity of acid phos- 

 phate of lime in the ash of this fat ; the other reactions of the fat 

 seemed also to confirm the presence of glycero-phosphate of lime, 

 which, as we have seen, is peculiar to the coloured blood-cells. 

 There is also an acid ammonia-soap contained in the fibrin- fat, 

 which may possibly have been conveyed to it by the serum. We 

 know so little of the non-saponifiable fats, that they cannot aid us 

 in deciding this question either negatively or affirmatively. 

 Virchow could not detect cholesterin in the fibrin of man, but 

 I have demonstrated its presence in the fibrin of horses by the 

 micrometrical measurements of its angles. It might indeed also 

 be derived from the serum. It follows from the above observa- 

 tions, that we are not as yet justified in ascribing special fats to 

 the fibrin. We might perhaps be disposed to attach some weight, 

 as far as this question is concerned, to Virehow's observation of an 

 acid reaction of the fat of the fibrin, but independently of the fact 

 that the fat of the coloured blood-cells exhibits a similar reaction, 

 there are several grounds for explaining this phenomenon. In the 

 first place, these fats, as they contain the salts of the fatty acids, 

 must assume an acid reaction whenever the ether which is 

 employed, is not entirely pure, (free from acetic acid, aldehydic 

 acid, &c.), and from several investigations in relation to this subject, 

 I am disposed to think, that the metamorphosis of the ether into 

 acids, by the action of animal substances, is considerably promoted 

 by prolonged digestion. On the other hand, we can the less 

 wonder at the acid reaction of these fats, since the salts of the 

 fatty acids precipitated with the fibrin by water, are acid salts, from 

 which on fusion volatile and acidly reacting fatty acids are sepa- 

 rated from their combinations with bases. Thus, for instance, we 

 constantly find volatile fatty acids in these fats (both in those of the 

 fibrin and of the blood-corpuscles), as for instance, acetic acid, 

 which may be produced by the metamorphosis of the ether, and at 

 least one acid, which, when treated with baryta, yields a salt which 



