THE CELLULAR BASIS 16] 



tween the different eggs or spermatozoa pro- 

 duced by the same individual, but the reactions 

 of these cells in development prove that they 

 are different. Undoubtedly chemical and 

 physical differences are here present but no 

 chemical methods at present available are 

 sufficiently delicate to detect them. The de- 

 velopmental test indicates that there are as 

 many kinds of oosperms as there are differ- 

 ent kinds of individuals which- come from 

 oosperms. It is one of the marvellous facts of 

 biology that practically every sexually pro- 

 duced individual is unique, the first and last 

 of its identical kind, and although some of 

 these individual differences are due to vary- 

 ing environment, others are evidently due to 

 germinal differences, so that we must conclude 

 that every fertilized egg cell differs in some 

 respects from every other one. 



But are there molecules and atoms enough 

 in a tiny germ cell, such as a spermatozoon, 

 to allow for all these differences? Miescher 

 has shown that a molecule of albumin with 40 

 carbon atoms may have as many as one billion 

 stereo-isomers, and in protoplasm there are 



