232 MISCELLANEOUS STUDIES 



Table 2 shows the numbers and percentages of apparent mutants 

 found in the cultures of 1910 and 1911F. Since the early type seems 

 to differ from Snowflake only in size and earliness, and is probably 

 inherited without special complications, the available progeny of early- 

 type parents are included in the totals. The progeny of all parents 

 recognized as belonging to other aberrant types are omitted. The 

 second column under ' ' Percentage of mutants ' ' omits doubtful types 

 and individuals, but includes some individuals for which some doubt 

 was indicated in the original records. One rare type of 1911, large- 



TABLE 2 



Aberrant types: occurrence among progeny of Snow flake and early parents. 

 Apparent selective elimination at or after germination in 

 field-sown cultures." 



Germination in greenhouse-sown lots, counting only plants examined for 

 type, 93.2 per cent; in field-sown lots, 45.1 per cent. 



"Including some plants of uncertain type, indicated for some lots (when 

 apparently not Snowflake) in tables 1 and 3. 



c For the calculation of these probable errors the percentages on the third 

 line are used as p. 



leaved, here omitted, has proved to be genetic, but its determination 

 in these cultures was in general uncertain. A stricter criterion for 

 the second column, elimination of all individuals not considered posi- 

 tively determined, was used in the calculations for the tables for the 

 inheritance of the separate mutant types. 



Evidently the more rigorous field conditions of 1911 eliminated 

 many of the "mutants' 7 at or soon after germination. The "coefficient 

 of mutability" with good germination, as was the case with the un- 

 selected cultures of 1908, seems to be near 5 per cent, a surprisingly 

 high figure if immediate true mutation is responsible. 



Before the aberrant types are considered separately, we may 

 examine (table 3) a detailed illustration of their occurrence in larger 

 cultures. It seems probable, from this evidence, that any descendant 

 of "WG9 was capable of producing any of the mutant types so far 



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