THE CELLULAR BASIS 91 



the result of reasoning about names rather 

 than facts, of getting far from phenomena 

 and philosophizing about them. The compari- 

 son of heredity to the transmission of property 

 from parents to children has produced con- 

 fusion in the scientific as well as in the popu- 

 lar mind. It is only necessary to recall the 

 most elementary facts about development to 

 recognize that in a literal sense developed char- 

 acteristics of parents are never transmitted to 

 children. 



2. The Transmission Hypothesis. And 

 yet the idea that the characteristics of adult 

 persons are transmitted from one generation 

 to the next is a very ancient one and was uni- 

 versally held until the most recent times. Be- 

 fore the details of development were known 

 it was natural to suppose, as Hippocrates did, 

 that white-flowered plants gave rise to white- 

 flowered seeds and that blue-eyed parents pro- 

 duced blue-eyed germs, without attempting to 

 define what was meant by white-flowered seed 

 or blue-eyed germs. And even after the facts 

 of development were fairly well known it was 

 generally held that the germ cells were pro- 



