THE PROTOPLASMATIC MEMBRANE 



in the metabolism of the cell, the assimilation of 

 food taken up from outside the cell and the 

 excretion of substances from the cell. The 

 plasmatic membrane is not completely permeable 

 for all substances, but has a so-called semi- 

 permeable layer, which permits some substances 

 to pass through and others not. The protoplas- 

 matic membrane is a compound colloid system 

 consisting of an extremely fine fat emulsion sus- 

 pended in a hydrosol, probably an albuminous 

 colloidal solution. We see, then, that fatty bodies 

 are taken up as well as watery solutions. Con- 

 cerning the latter, we are able to show how im- 

 portant adsorption phenomena are in assimilating 

 them. The laws of adsorption govern the assimi- 

 lation of salts from the soil. Even the action of 

 acids can be produced by adsorptive election. 



So we may say that a great many phenomena 

 in life once attributed to Life Force, and not to be 

 explained by chemical laws, can in the present 

 stage of science be reduced to the general Laws of 

 Nature. 



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