F. C. Miles 195 



This vegetative segregation concerned only the leaf colour. When a 

 white-leaved type and a green-leaved type were crossed and the parents 

 differed in some other character, e.g., flower colour, then the flower 

 colour Mendelized regularly. 



In 1910 Baur (4) reported the occurrence of pure white-leaved plants 

 in Melandrium, Antii'rhinnm, and Phaseolus vulgaris. He had not fully 

 investigated the case of Phaseolus, but in both Melandrium and Antir- 

 rhinum the white condition proved to be a simple recessive character. 

 He believes that in Antirrhinum several factors are concerned in the 

 formation of leaf colour. 



Analogous examples of the inheritance of the variegated condition 

 of leaves have been reported by Baur (4) for Aquilegia vulgaris, and by 

 CoiTens(6) for Mirahilis jalapa. The leaves of the plants have irregular 

 spots of a very light-green, or almost white, colour. Crossed with green 

 plants the F^ is green and F^ segregates into approximately three green 

 plants to one variegated plant. The variegated individuals when self- 

 pollinated usually breed true to the variegated condition, but occasion- 

 ally a fully-green plant occurs. Some of these green plants when self- 

 pollinated yield only green progenies, but others segregate into green 

 plants and variegated plants. The cause of this apparent inconstancy 

 of the variegated segregates is not fully understood. 



East and Hayes (9) in 1911 mentioned the occurrence of striped 

 leaves in some of their cultures of maize. The striped plants were 

 apparently heterozygous, and when crossed with normal green plants 

 green was dominant. Progenies from striped plants consisted of green 

 plants, striped ones, and plants lacking chlorophyll. These latter died, 

 but, as the authors suggested, very probably were homozygous recessives. 



Emerson (10) in 1912 reported his studies of various degrees of 

 chlorophyll reduction in maize, and described a number of types which 

 he had not fully investigated. He found pure white seedlings void of 

 chlorophyll, and which therefore died at any early age. In inheritance 

 he showed the character to be a simple Mendelian recessive. 



In some of his cultures there were individuals which were almost 

 void of chlorophyll, but there was sufficient colouring material to give 

 the seedlings a yellowish-white appearance. Seedlings of this type 

 may turn more or less greenish, but at the time of his publication none 

 of the plants had lived longer than seven weeks. This character also 

 behaved as a simple Mendelian recessive. 



The third type which he described concerned the partial reduction 

 of chlorophyll in growing and mature plants, resulting in a distinct 



13—2 



