MUTATION IN MATTHIOLA 259 



shows in its progeny any evidence of belonging to the early type ; the 

 means are slightly lower than for the many-noded sibs of these parents, 

 but far less so than with the parents descended from WG9-C10. 



We conclude, then, that WG9-C10 was probably a monohybrid, 

 and that the early-bearing gamete entering into its composition was of 

 unknown but presumably mutative origin. 



Most of the extracted late or many-noded parents may now be 

 selected with practical certainty. "WG9-C10-C8 and Cl (lots 5 and 6 

 in the 1911F cultures) and WG9-C10-M7 and M8 (lots 13 and 14) 

 were genetically very similar to the check parents, as has already been 

 concluded for two of them from the greenhouse cultures ; presumably 

 they were pure Snowflake. 



The data for WG9-C10 itself (lot 26) seem to indicate that the 

 results from the last eight lots are of very doubtful value ; still, they 

 show, especially in the original individual records, some evidence of the 

 earliness factor which must be present in part of the individuals. The 

 poor and slow germination of the old seed available may have had an 

 important influence on the result ; many of the early embryos may have 

 been non-viable, and the seedlings may have been weaker than those 

 from fresh seed. The 1911 data and observation of the plants in the 

 field suggest that WG9-C10-W7, W3, and W10 (lots 23, 24, and 25) 

 are the only remaining extracted late parents, WG9-C10-W5 and W8 

 (lots 21 and 22) carrying the earliness factor, as the four parents just 

 preceding them in the cultures obviously did. Tables 22 and 23 con- 

 firm this conclusion for WG9-C10-W8. 



It is presumably impossible to make a positive separation of the 

 parents homozygous for the presence of the early factor. The green- 

 house data suggest that WG9-C10-M4 was a pure early individual; 

 the field data (see lot 9) agree, and suggest that WG9-C10-M9 (lot 

 10) and perhaps WG9-C10-M6 (lot 11) belong in the same class. 

 WG9-C10-C2, C5, and CIO (lots 3, 4, and 40) 12 were all evidently 

 heterozygous. Of the parents grown in house W, it would seem that 

 only WG9-C10-W11 (field lot 19) was homozygous early. We have, 

 provisionally, for the available single progeny of WG9-C10: 



House House M House W Total 



Pure early 0314 



Hybrid early 3159 



Pure late 2237 



20 



12 Statistical data given for the last only for the 1910 cultures, not for this 

 field lot. 



[1171 



