66 ESTABLISHMENT OF VARIETIES IN COLEUS 



Later the leaves formed may show increased amounts of yellow, until 

 by midsummer the plant is uniform for the green-yellow-red blotched 

 pattern. Figures 14 and 14a show winter and summer conditions quite 

 general for the leaves of the yellow-green pattern, which indicates that 

 cells may be either green or yellow. Furthermore, all degrees of varia- 

 tion can appear as bud variations affecting segments of a bud. 



Such conditions indicate that all the cells are potentially green. 

 If this be accepted, a further point is raised regarding the source of 

 the influences leading to loss of green and to development of yellow in 

 its place. In respect to the final action in the cells, change from green 

 to yellow is itself apparently a local phenomenon in that local action of 

 plastids is affected. 



The fluctuations and variations in the extent and position of the 

 green and yellow tissues, however, indicate that here, as in the develop- 

 ment of red, certain intercellular influences are operating. The con- 

 figurations of the yellow and green areas, as well as that of the red, are 

 in marked degree bounded by veins. For the green and yellow this 

 is most strikingly shown in figures 12 and 14. For the red similar 

 conditions are seen in any of the blotched patterns, as, for example, 

 figures 2 and 5. This also indicates that the flow of substances giving 

 different centers of distribution and concentration is the important 

 factor in the production of patterns. 



In respect to the extent and degree of the variations, it has already 

 been pointed out that no plant in my cultures of Coleus has been 

 obtained without some red coloration in some part of the plant. In 

 regard to yellow, however, there were frequently fluctuations and bud 

 variations giving branches with no yellow. The loss of yellow appears 

 to be complete in a manner that suggests loss of hereditary qualities 

 through segregations, but even in constant selection of pure-green stock 

 for vegetative propagation about half of the offspring show return to 

 patterns containing yellow both by fluctuations and by bud variations, 

 with, also, cases of marked spontaneous appearance of yellow in a few 

 or in single leaves. To say that the power to produce yellow has been 

 latent is to say that the conditions causing its development can arise 

 in an apprently spontaneous manner. 



While the evidence indicates that the ability to produce green, 

 yellow, and red is a metidentical property of the cells, it is equally 

 clear that these metidentical properties do not exist as units. They are 

 subject to interaction between cells. They are more or less perma- 

 nently modified either by the intercellular relations or by spontaneous 

 intracellular changes. The records of pedigree show very clearly that 

 tendencies to give vegetative progeny of different degrees of constancy 

 and variation arise or exist in sister branches that are apparently 

 quite identical. Such tendencies detected by the pedigreed cultures 

 have already been mentioned. The production of branches which give 



