GENETICS 101 



it, a vast majority of the genes occurring in the 

 body are inactive. Such a condition appealed to 

 me as entirely out of harmony with the known 

 facts of organic activity. Wherever we find organic 

 units of higher degree associated, each retains the 

 structures which are actively or potentially of use 

 to it; other parts may persist for a long time but 

 they tend to disappear. This led me to propose the 

 hypothesis that genes may act upon cells other 

 than those containing them, so that a given char- 

 acter may be the expression of many similar genes 

 throughout the body, rather than of those in the 

 cells expressing the character alone. If the nucleus 

 acts by the production of enzymes their transporta- 

 tion to other cells is not impossible, but it is not 

 known to occur. 



At the time of formulating this conclusion I 

 recognized the apparently contradictory nature of 

 gynandromorphs. Recently Go wen has added a 

 discussion of mutations induced in somatic cells of 

 Drosophila by the use of X-rays, which he regards 

 as absolute proof that the activities of genes are 

 limited to the cells containing them.^^ Patterson ^^ 

 recorded the occurrence of similar localized muta- 

 tions in Drosophila. Eye mutations even occur in 

 such limited areas as a few ommatidia, so that a 

 red eye may show a small white patch or isolated 



24 Science N. S., Vol. LXX, pp. 358-360, 1929. 



25 Ibid., Vol. LXVIII, pp. 41-43, 1928. 



