98 HEREDITY AND ENVIRONMENT 



by the adult animal or plant and that the 

 characteristics of the adult were in some 

 way carried over to the germ cells; but the 

 manner in which this supposed transmission 

 took place remained undefined until Darwin 

 attempted to explain it by his "provisional 

 hypothesis of pangenesis." Darwin assumed 

 that minute particles or "gemmules" were 

 given off by every cell of the body, at every 

 stage of development, and that these gem- 

 mules then collected in the germ cells which 

 thus became storehouses of little germs from 

 all parts of the body. Afterward, in the devel- 

 opment of the embryo, the gemmules, or little 

 germs, developed into cells and organs similar 

 to those from which they originally came. 



3. Germinal Continuity and Somatic Dis- 

 continuity. — Many ingenious hypotheses have 

 been devised to explain things which are not 

 real, and this is one of them. The doctrine 

 that adult organisms manufacture germ cells 

 and transmit their characters to them is now 

 known to be erroneous. Neither germ cells 

 nor any other kind of cells are formed by the 

 body as a whole, but every cell in the body 



