178 



AN INTRODUCTION TO MODERN GENETICS 



into a en host, the host supplies v substance from which the eye can 

 make its own en substance and develop wild-type pigment. Thus the 

 lack of en substance in v eyes is simply due to lack of v substance to 



I 1 CZD ^ 



h 



z 



< 

 J 



a 



Fig. 84. The Results of Transplantation of Eye Discs in Drosophila. — Shaded 

 circles indicate "autarchic" development, i.e. no influence of the host. Black 

 circles indicate that the implant develops "hyparchically" in that combination, 

 i.e. acquires the colour of the host eyes. If the influence of the host is incomplete 

 the circle is shown partially black. The genes used are as follows: bo bordeaux, 

 bw brown, ca claret, car carnation, cd cardinal, cl clot, cm carmine, cn cinnabar, 

 g2 garnet-2, Hrf Henna recessive, It light, ma maroon, pP peach, pd purploid, 

 pn prune, pr purple, ras raspberry, rb ruby, se sepia, sed sepiaoid, sP safranin-2, 

 St scarlet, v vermilion, w white, w^ apricot, we eosin. 



(From Beadle and Ephrussi.) 



make it from. As would be expected, cn eyes in v hosts remain en in 

 colour. 



In the eay em, p^ and rb eyes a process must have occurred which not 

 only interrupts the chain of synthesis but which also makes the tissues 



