1 8 THE NEW CELL DOCTRINE 



two functions of the nucleus, which are usually carried out by 

 a single unitary nucleus. 



Vital phenomena rest on chemical processes by which 

 energy is set free to show itself through the activities of the 

 living being. 



The first thing which the beginner learns is that chemical 

 change, or metabolism, plays the chief role in aU biological 

 phenomena. The biologists describe the intake and excre- 

 tion of the nutritive material, and attempt to trace the change 

 to which this material is subjected in the ceU. CeUs possess, 

 of course, no mouth. They can absorb material only through 

 their surfaces. Therefore the surface of every cell is of the 

 utmost importance for the continuation of its life, and the 

 investigation of this surface and its tension has been eagerly 

 pursued of late. Important results have already been pro- 

 duced; as, for example, it has been discovered that the surface 

 tension during the impregnation of the ovum must be changed 

 if the spermatozoon is to enter, and after the spermatozoon 

 is in the interior of the egg the surface tension is again changed. 

 The gifted German-American inve;stigator, Jacques Loeb,'' 

 has advanced the hypothesis that the egg has a superficial 

 layer of lipoid substance which at the time of impregnation 

 passes into a soluble condition. This hj^othesis has since 

 been confirmed by the experiments of Ralph L. LilUe.^ 



The egg of the sea urchin, after remaining some time in 

 sea water, becomes more resistant so that the spermatozoon 

 cannot penetrate the eggs as easily as when they were fresh. 

 If such resistant eggs are treated with sea water, to which one 

 has added 0.3 per cent, of ether, by which supposedly lipoid 

 substances are dissolved, it is found that the eggs are more 

 easily fertilized. But even if Loeb's hypothesis is not ab- 

 solutely correct, the phenomenon itself remains extremely 



