262 MISCELLANEOUS STUDIES 



of the leaves, and of general convexity of the upper surface of the 

 leaves. Mature plants developed under favorable conditions in the 

 greenhouse closely resembled Snowflake; the leaves, however, were 

 noticeably brittle, and the dry capsules so brittle that it was often 

 necessary, as it was not with Snowflake, to shell the seeds individually. 

 Probably the fibrovascular system is in some way defective ; Oenothera 

 rubrinervis, which is also brittle (deVries, 1906, lecture 18), has 

 thin-walled bast fibers. 



In the field cultures, both at Ithaca (fig. 5) and at Riverside, under 

 conditions less favorable on the whole to the initiation of flowering, 

 this type (fig. 8) differed much more widely from Snowflake. Flower- 

 ing was excessively delayed, and the plants often remained low, with 

 few branches, and rosette-like, with thin, rather narrow leaves. Small 

 brown dead spots, possibly due to excessive transpiration, occurred so 

 frequently on the leaves as to constitute a good diagnostic character 

 for the type. Another peculiarity observed in the field is a reflexed 

 position of the tip of the young leaf when first visible Snowflake 

 leaves being completely erect from the first. 



In the 1914 cultures, with better development than in other field 

 cultures, some smooth-leaved plants (figs. 9 and 10) were again more 

 like Snowflake, though later and evidently more leafy. 



Six smooth-leaved parents have been used in progeny tests, three 

 of these being apparent mutants and three being F a progeny of two 

 of those mutants. The results are presented in tables 24 and 25 ; these 

 tables require a brief explanation, which will apply also to the similar 

 tables for other types. 



For the plan of the new pedigree numbers here used, see ' ' Methods. 

 The initial plants of a series are designated as the P x generation in 

 the tables, their progeny as F,, etc. In table 24 the cultures are 

 arranged according to their generations and their pedigree numbers 

 under each generation; the smooth-leaved parents (P t or of the P, 

 type) are given first, followed by the extracted Snowflake parents. 

 In table 25 "good germination" indicates that in all lots included 

 (taken as grown, not as summed by parents in table 24) the number 

 of plants determined exceeds 50 per cent of the number of seeds sown, 

 and vice versa; the weighted mean percentages obtained by dividing 

 the total numbers of plants by the respective total numbers of seeds 

 are given for each table in a footnote. 



All six smooth-leaved parents (tables 24 and 25) gave mixed 

 progeny, part smooth-leaved and part Snowflake. The surprising 



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