166 BLOOD. 



while those of the blood of the portal vein (simultaneously col- 

 lected from the same animal) possess a very considerable sinking 

 tendency; this may be very readily explained by the preceding 

 observations ; the difference between the density of the cells and 

 of the serum is far more considerable in portal blood than in that 

 of the hepatic veins ; in the former, according to my experiments, 

 the density of the serum is to that of the cells as 1 : 1*062, and in 

 the latter as 1 : T053. The serum of the blood from the hepatic 

 veins contains (relatively to the other constituents) far less 

 albumen than that of the portal vein ; and, lastly, the corpuscles 

 of the former blood are far poorer in heematin than those of the 

 latter. 



It is moreover not impossible that, at all events in certain cases, 

 there is a converse relation of the causal action to that which we 

 have hitherto assumed ; for it is quite conceivable that the sink- 

 ing of the cells is less dependent on their adhesion, than the 

 adhesion on the gravity of the corpuscles : the viscidity of the 

 cells can at all events not be great ; for the slightest mechanical 

 actions are sufficient to break up the nummular rolls and their 

 branches into fragments consisting only of a few cells, which, if 

 there were any considerable degree of viscidity, would be impossi- 

 ble. We may regard the following as the order in which the 

 phenomena occur : a more or less active motion is excited in the 

 molecules of the blood, by the difference in the gravity of the 

 blood-cells and the intercellular fluid ; and the more active the 

 motion is, so much the more frequently will the cells be pressed 

 together, and have the opportunity of cohering, in the same man- 

 ner that a fresh precipitate, as, for instance, of chloride of silver, 

 conglobates much more readily when the fluid and the precipitate 

 are well stirred. If an approximation of the blood-corpuscles is 

 rendered possible by the motion excited in the above mentioned 

 manner, these discoid bodies can scarcely attract and adhere to 

 each other, except by their surfaces ; and that the plasma subse- 

 quently would offer less resistance to the sinking of the rolls than 

 to that of the individual corpuscles, might be inferred from the 

 analogous case of the chloride of silver, even if it were not 

 obvious from physical laws. Nothing, however, but an extensive 

 series of comparisons between the density of the blood-cells and 

 that of the plasma, and a combination of these results with the 

 observed sinking tendency, can enable us to come to a certain 

 decision regarding this view : at present we must, at all events, 

 assign to the density a considerable part of the sinking tendency 

 of the blood-cells. 



