1762 PLANT-BREEDING 



some white plants were raised in addition to the normal green ones. Ninety 

 out of lou seeds of Elite ^/j^ge^minated; of these 75 plants were normally green 

 and 15 (representing 16.6 per cent) were pure white without a trace of green 

 colour. These white plants developed normally as long as the reserve food 

 materials in the seeds lc.sted ; the}^ formed two leaves of normal size and 

 thickness, biit after 3 or 4 weeks they died because assimilation could not 

 be carried on. Of the 75 green descendants of Elite ^j^^, 47 were eaten by 

 insects during the year, 28 plants were harvested and 6 of these were select- 

 ed for further investigation. All the seeds from these 6 plants were sown 

 separately in autumn 191 5. The other 22 plants were harvested and sown 

 together. 



The descendants of two of the 6 plants which were sown separately were 

 normal and green, those from the other 4 being mixed. From the batch of 

 22 plants 10 960 seeds were sown and 9 646 plants were obtained, of which 

 8 412 were normallj" green and i 234 weie white. Theoretically these figures 

 may be explained thus. 



C = presence of chlorophyll (doiiiinatit) 



c = absence of chlorophyll. 



Generation Pj : C c 



Generation Fj : Cc 



Generation Fg : CC Cc Cc cc 



If the 22 plants had all been equally prolific each plant would have produced 438 descen- 

 dants, so that in Fj 



CC 



3 215 



The 3215 CC are constant in the Fg generation ; the 6 430 Cc, on t he other hand, subdivide 

 thus : 



CC Cc cc 



I 607 3 214 I 607 



Thus there would be 



3 215 homozygotes of Fg 

 I 607 homozygotes of Fg 

 3 214 heterozygotes of Fg 



Total 8 036 green plants. 



The theoretical calculation gives S 036 green and i 607 white plants in 

 the Eg generation, whereas actually 8 412 green and i 234 white plants were 

 obtained . This difference may be explained by the fact that an average num- 

 ber of grains was reckoned for each plant and also that only 22 plants, with 

 a large number of tillers, were dealt with. The proportions between the 

 numbers of green and white descendants of the six plants sown separately 

 show quite clearly that etiolation is transmitted as a recessive character ac- 

 cording to Mendel's law, thus confirming the residts of Nilsson-Ehle, 

 Vestergaard and Miles. 



It is interesting to notice that in this case, in which the crossing was 

 carried out in exact accordance with scientific rules, the characters were trans- 



