1924] 



Collins: Inheritance in Crepis capillaris (L.) Wallr. 



273 



of yellow and green through the leaves, which looks much like the 

 plant disease known as ' mosaic, ' or rosettes on which the central and 

 thus younger leaves of the plant are a clear yellow. These yellow 

 leaves later develop chlorophyll and become normally green. 



It would appear from table 15 that the golden yellows would be 

 homozygous recessives ; but this is not the case, for the seedlings from 

 self ed /yellow center' and from 'mottled' plants show some of them 

 to be heterozygotes. Only one plant has 3^et been found which was 

 homozygous for yellow. 



TABLE 15 



MONOHYBRID SEGREGATION OF GoLDEN YeLLOW IN THE PROGENY OF 



Green Plants 



That there are other genes which also produce yellow seedlings is 

 evident from table 16. The three plants P..,;,, ,;,.,, and -,3 were green 

 as seedlings and normal green in the mature stage. They apparently 

 were heterozygous for two recessive genes which produced the same 

 or a very similar type of yellow. The progeny of P^-, indicate still 

 another type of yellow indistinguishable phenotypically from those 

 already mentioned. Here the production of chlorophyll in the seed- 

 ling stage is dependent on the simultaneous presence of two dominant 

 genes, and the absence of either one results in a yelloAV type of 

 seedling. 



Trow (1916) reports a similar case of complementary recessive 

 genes in the production of albino seedlings in Senecio, another genus 

 of the Compositae. 



