MV TAT ION IN MATTHIOLA 229 



WG9-C10 made in 1910-11 ; all available progeny of WG9-C10, except 

 the crenate-leaved apparent mutant WG9-C10-C10, were tested, with 

 check lots between as before. Soil differences and unavoidable differ- 

 ences between lots in time of transplanting combined with hot weather 

 and drought to reduce the value of the results. The remaining fifty- 

 two lots, all field-sown, included a further test of the heredity of 

 aberrant types other than early. Most of these lots, however, were 

 progeny of Snowflake parents, grown to obtain evidence on the relation 

 of temperature to mutation and on the inheritance of doubleness of 

 flowers, and therefore the results are not reported here. 



The 1911H cultures constituted a coldframe and greenhouse prog- 

 eny test of mutant types, mainly in the second generation, the plants 

 being grown in flats. 



There was added in 1912-13 a small greenhouse test bearing on the 

 supposed mutative origin of WG9-C10, in view of the apparent possi- 

 bility that "WS1 or "WL10, in the same house with the unbagged WG9, 

 might have been heterozygous for the early type cross pollination 

 then giving the apparent mutant. 



Further progeny tests of the mutant types have been made in the 

 field at Riverside, beginning in the fall of 1913. Mainly on account 

 of the unsuitability of the usually hot and dry climate of River- 

 side, the cultures have been largely experimental and always on a 

 small scale, and germination or development has sometimes been un- 

 satisfactory. Cultures have been started in October, November, 

 January, and February, and a trial culture in progress at the time 

 of writing was started in August. Some of the plants of the 1915-16 

 cultures were kept until the summer of 1917, and many of them 

 flowered for the first time when about a year old. 



In the cultures of 1913, growth was largely unsatisfactory, and 

 with part of the plants aphid injury interfered more or less with the 

 classification of types. In the cultures of 1914, the seeds were largely 

 lost through toxic effects favored by very shallow planting (as at 

 Ithaca) and strong evaporation from the soil. In subsequent planting, 

 the seeds, planted singly in small paper pots, were dropped into 

 relatively deep holes punched in the soil, and covered with sand. 



The only field-grown plants closely resembling those grown in the 

 greenhouse at Ithaca, it may be noted, have been those of the 1917 

 cultures, grown in a lathhouse with added shade from muslin. 



In the cultures of 1915-16, with partial shade and more frequent 

 irrigation than before, development was in general good; but even 



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