CROSSING. 



93 



work 



done by de Vries and the botanists following him, 

 gradually began to turn into something 

 like irritation when we saw these authors 

 plunge deeper and deeper into their spec- 

 ialty. We saw how they accepted the most 

 startling, and to our mind exceptional 

 phenomena, as something to be taken for 

 granted, and how they kept on piling up 

 astonishing facts with a decided uncon- 

 cern for the possibility of an explanation 

 in terms common to the whole of Genetics. 

 The paper of Nilsson removed a great deal 

 of the tension, as it showed us the possi- 

 bility of understanding something of the 

 mysterious thing which we were all hoping 

 the specialists would investi- 

 gate, but which they had 

 until the time only taken 

 for granted. 



There is some danger, that 

 the Drosophila specialists 

 will cut themselves off from 

 the possibility of intercourse 

 with the other Geneticians as 



JZD 



35 tfl t5 W 5! «0 65 » ?5 « SS -» <55 VO 105 110 115 190% 



Fig. 14. 

 Variability in F2 from cross be- 

 tween Japanese dwarf x large 

 white mice. Weight expressed in 

 percentages of standard weight. 

 Males and females at 11, 12, 13 

 and 14 weeks. 



completely as de Vries and the 

 other Oenothera specialists. 

 Already they are writing in 

 terms which are not the terms 

 of the general Genetician, and 

 which evidently are perfectly 

 clear and reasonable to the 

 initiated, but astonishingly 

 unfamiliar to a great many 

 of us. 



It seems impossible to speak 

 of what happens in their cult- 



P-T 



? 



17* xm 



3 



172 *3« 



*5 50 55 60 6S ;o 75 60 85 00 Q5 KO 105 "0 115 1»% 



Fig. 15. 



Two sisters, 1 74 and 1 72, bred 



from Fl x large white, and their 



offspring from large white males. 



Weight expressed in percentages. 



