Phenomena of " Clot " Formations. 



373 



in the order in which they inhibit the gel formation, the more active 

 substances being placed first in the list. The numbers given are the 

 strengths in which they produce narcosis of tadpoles according to Overton. 



The concordance between the gel inhibitory action and the narcotic action 

 is striking. Methyl propyl ketone is an apparent exception, but gel-inhibiting 

 action of this substance cannot be accurately determined, as in relatively 

 small concentrations it causes the formation of crystals. The same is true 

 for ethyl alcohol in higher concentrations. Normal propyl alcohol should 

 follow instead of preceding urethane. The substances showing a marked 

 deviation from the surface tension generalisation are indicated in large 

 type.* 



General Summary and Conclusions. 

 The inhibition of gel formation may be assumed to be due to adsorption of 

 various substances from solution, which prevent the formation of larger 

 aggregates, which constitute the gel.f The adsorbability of those substances 

 cannot be determined by their effect alone in lowering the surface tension of 

 water. Czapek has assumed that certain plant cells have a lipoid membrane, 

 with a surface tension of about - 681 (water = 1), and that, when they are 

 immersed in an aqueous solution, the surface tension of which has been 

 reduced to below this figure, exosmosis of complex molecules takes place, 

 owing to the changes in the lipoid membrane. Czapek found, however, that 

 certain substances deviated from his rule. To these he ascribed a specific 

 toxic action on the cell. In view of the fact that these same substances 

 show a deviation also from a surface tension rule in their inhibitory action 

 on the formation of the cholate gel, a phenomenon from which specific 

 biological action is excluded, the purely mechanical conception of cytolysis, 

 as propounded by Czapek, is clearly no longer tenable. JSTor do the results 

 in the above paper support the Overton-Meyer lipoid hypothesis. Although 

 the lipoid soluble substances have, as a rule, the greatest inhibitory action on 

 gel formation, the gel itself cannot, by any extension of the meaning of the 

 term, be described as a lipoid. It is formed from the salt of an acid, which 

 is generally insoluble in organic solvents, in which even the free acid itself 

 is only slightly soluble. The results suggest that the semipermeability of the 

 cell may owe its properties to the presence of some gel-forming substance 



* Several estimations of the surface tensions of solutions have been made by different 

 observers. Czapek's own numbers have been adopted. In arranging the above table the 

 approximate dilutions which delay gel formation 15 minutes have been ascertained. The 

 surface tensions of these dilutions in water lies normally between 0'5 and 0'67 (water = 1). 

 The substances indicated in capitals deviated markedly from these numbers. 



t Compare Schryver, 'Eoy. Soc. Proc.,' B, vol. 83, p. 96 (1910). 



