152 Organisms from Eggs 



adds only the finer details to the rough block. Such a 

 possibility exists, and if it should turn out to be true 

 we should come to the conclusion that the unity of the 

 organism is not due to a putting together of a number 

 of independent Mendelian characters according to a 

 ''pre-established plan,'* but to the fact that the organ- 

 ism in the rough existed already in the cytoplasm of 

 the egg before the egg was fertilized. The influence 

 of the hereditary Mendelian factors or genes consisted 

 only in impressing the numerous details upon the rough 

 block and in thus determining its variety and individ- 

 uality; and this could be accomplished by substances 

 circulating in the liquids of the body as we shall see 

 in later chapters. 



