HAPTOGENIC MEMBRANES 429 



of protein, condensed about a fat globule by surface tension, 

 may become still more condensed by these very processes of 

 separation (passing through a layer of water, centrifuga- 

 tion), rendering it a firm and separable structure. That 

 coagulative phenomena may take place in the adsorbed 

 surface layer of a colloidal solution has been repeatedly 

 emphasized, and by Kreidl and Lenk for milk especially. 83 

 These latter writers have, too, proposed a very simple 

 experiment, which in the author's opinion distinctly contra- 

 dicts the idea of an organized nature for the haptogenic mem- 

 branes. It is well known that the theory of the haptogenic 

 membrane is based on the fact that fat is not separable from 

 cow's milk by merely shaking with ether, but can be accom- 

 plished only after first treating the milk with potassium 

 hydrate solution. This has been interpreted as indicating 

 that the potash solution dissolves the " membrane " which 

 encloses the fat globule and protects it from the penetration 

 of the ether. Kreidl and Lenk, 84 however, have found that 

 when a drop of milk is placed on Losch carton it divides into 

 three concentric zones as the result of capillary adsorption ; 

 in the central zone the suspended fat remains behind, in the 

 middle zone the imperfectly dissolved casein, while the water 

 and fully dissolved materials (as sugar) pass furthest and 

 are to be found in the outer ring. If the milk be rich in 

 fat there remains in the centre a large proportion of a butter- 

 like material, which is readily soluble in ether (particularly 

 apropos to the matter in hand). To the writer's mind this 

 seems altogether at variance with the assumption of an 

 organized nature of "milk-stromata" or "haptogenic mem- 

 branes." It would be impossible to think that they are 

 stripped away from the individual fat globules in the course 

 of distribution of the milk in the Losch paper. The facts 

 probably are that the insolubility of the milk fat in ether is 

 connected with the presence of ultra microscopic particles of 



83 A. Kreidl and E. Lenk (Vienna), Pfluger's Arch., 1^1, 558, 1911. 



84 L. c., pp. 543-549. 



