282 



DIFFUSION, OSMOSIS, AND FILTRATION. 



1. Egg albumin 4'14 per cent, proteids ; pressure, 32'5 cm.; goldbeater's skin. 



(Filtrate per minute in grms. , '820, '051, '008, '003, '002, '002.) 



2. Ox serum 4 '5 per cent, proteids ; pressure, 30 '5 to 34 cm. ; goldbeater's skin. 



(Filtrate per minute in grms., 2'586, 1-594, TOGO, -812.) 



In neither case had the membrane been previously stretched. 



According to Gottwalt, 1 the serum albumin of blood serum niters 

 through a ureter more easily than the globulin. Martin 2 has shown 

 that homogeneous membranes of gelatin and gelatinous silicic acid form 

 filters impermeable to solutions of many colloids, but as permeable 

 to certain crystalloids as to water. 



The relation of the concentration of the filtrate to that of the 

 original solution is perhaps the most important point to the physiolo- 

 gist in the matter of filtration through* animal membranes. There is 

 general agreement that in the filtration of crystalloids the concentration 

 of the filtrate is very nearly that of the original solution, and this 

 appears to obtain at very various filtration pressures. 3 There is also 

 general agreement that in filtration of colloids the concentration of the 

 filtrate is always less than that of the original solution. 4 But as regards 

 the effect of pressure on the concentration of a colloid filtrate, the 

 results of different observers are not in accordance. Kuneberg 5 has 

 maintained that the concentration of the filtrate is higher at lower 

 than at higher pressures, and the following table, taken from his later 

 paper, 6 is illustrative : 



Fresh Sheep 7 s Intestine Ascitic Fluid (circulated) holding 

 3 '7 2 per cent, of Proteids. 



1 Loc. cit. 2 Journ. Physiol., Cambridge and London, 1896, vol. xx. p. 364. 



3 Schmidt, urea, sodic chloride, and potassium nitrate, Ann. d. Phys. u. Chem., 

 Leipzig, 1861, Bd. cxiv. S. 391. 



4 Schmidt, loc. cit., gum and albumin through ox -pericardium ; Hoppe-Seyler, Virchow's 

 Archiv, 1856, Bd. ix. S. 245, blood-gerum through ureter ; Eurieberg, loc. cit., gut, 

 ureter, and pleural membrane, with serum, ascitic, and pleuritic fluids ; Gottwalt, loc. cit., 

 egg albumin, hydrocele fluid, serum, and parovarian cyst fluid through ureter. 



5 Loc. cit. " 6 Ztschr.f. physiol. Chem., Strassburg, 1882, Bd. vi. S. 508. 



