14 Plant Genetics 



germ plasm, with its result on the doctrine of the inherit- 

 ance of acquired characters, is still current. The first 

 result of Weismannism was to overshadow Darwin s 

 theory of pangenesis, which had unjustly shared the 

 deserved fate of its companion theory, the transporta- 

 tion hypothesis. De Vries (2) was the first to recog- 

 nize this injustice, and in 1889 published his Intracellular 

 pangenesis. Without attempting to defend the trans- 

 portation hypothesis, De Vries showed the real value 

 of the doctrine of pangenesis. He claimed that his 

 theory of intracellular pangenesis is Uttle more than a 

 restatement of the fundamental ideas of Darwin's 

 pangenesis, but in fact it contains enough new material 

 to justify a definition. 



The material particles which De Vries conceived 

 of as the carriers of heredity he called pangens, the 

 equivalent of Darwin's gemmules. He claims that in 

 the nucleus every kind of pangen of the individual is 

 represented, while the cytoplasm in each cell contains 

 only those pangens that become active in the cell. He 

 concludes that, with the exception of the pangens con- 

 cerned in nuclear activities, such as nuclear division, 

 all pangens have to leave the nucleus in order to become 

 active. But most of the pangens of almost every kind 

 are represented in the nucleus, where they multiply, 

 partly for the purpose of nuclear division, partly to pass 

 into the cytoplasm to engage in other activities. These 

 pangens not only pass out into the adjacent cytoplasm, 

 but are also carried by the protoplasmic currents into 

 the various organs of the protoplast, where they multiply 

 and become active. All protoplasm consists of such 

 pangens derived at different times from the nucleus 



