366 Tricot yl oils Races. 



Oenotheras differ from the parent species in several char- 

 acters ; nevertheless each arises siuklenly with its char- 

 acters complete. From this fact we conclude that all of 

 them must be regarded as the expression of a single m- 

 ternal change. A single new elementary character can 

 thus affect more or less profoundly a whole group of 

 older internal characters. 



We will regard tricotyly, for the present at any rate, 

 as the primarv expression of a definite internal factor 

 wliich occurs in the latent state in large numbers of di 

 cotvledons. though not necessarily in all. It also occurs, 

 although as yet in a small group of cases, in the active 



:? ^-'-^ 



Fig. 7^. Scrophi'.lan'a nodosa. A tricotyloiis seedling with the 

 first whorl of leaves which is ternary also; C, the cotyl- 

 edons, l-'rom the harvest of 1899. 



State alongside dicotyly. On this point of view the qties- 

 tion suggests itself whether this internal factor will per- 

 ha])s also betray itself during the later life of the plant. 

 I^ricotvly results in an abnormal arrangement of the 

 seed-leaves, and thus it is only natural to expect that its 

 internal cause may lead to anomalies in the disposition 

 of the foliage leaves as well. 



As a matter of fact, this is the case. In the first 

 place, in species with decussate leaves, the arrangement 

 of the leaves in whorls of three may continue upwards 

 from the cotvledons fFig. 73V This may be limited to 



