MUTATION IN MATTHIOLA 285 



The few singles have produced few seeds, and these were highly 

 variable in size. The capsule often has a defective septum, more or less 

 of the distal portion being absent. Germination was poor in the small 

 cultures secured (table 38, upper part), with only 10.8 per cent of the 

 mutant type among the progeny. 



This case agrees in most respects with those previously discussed, 

 but adds one point of interest in the occurrence of apparent coupling 

 of mutant type with doubleness rather than singleness. Seed appears 

 to be less abundant and less well developed than with any of the pre- 

 ceding mutant types, facts probably significant in relation to the low 

 percentage of narrow progeny from narrow parents, though the large 

 probable error of the percentage must be considered. 



7. MISCELLANEOUS ABERRANT TYPES 



As part of the aberrant individuals occurring in the greenhouse 

 were either doubles or singles that produced no seed, while practically 

 no seed was produced by any plants in the field at Ithaca or by even 

 some of the commoner mutant types at Riverside, the opportunity for 

 progeny tests has been almost entirely limited to the types so far 

 discussed. 



The narrow-dark-leaved type (table 3) was common and distinct 

 in the field at Ithaca, where it constituted about .48 per cent of the 

 2072 plants from house-sown seed, and has been readily identified 

 in several cases at Riverside. It was not distinguished in the green- 

 house cultures, but was very probably included under narrow-leaved. 

 Possibly a single described as "small-convex-leaved" belonged to this 

 type, though two field plants were given this name as distinct from 

 narrow-dark; according to a photograph (fig. 25, second plant from 

 left), another greenhouse plant (a double) may have been similar to 

 narrow-dark-leaved. The narrow-dark-leaved type (figs. 26 and 27) 

 has narrow dark-green leaves, strongly convex upward, and evidently 

 tends to compactness of growth and lateness of flowering ; under field 

 conditions it seems decidedly more like Snowflake than like narrow- 

 leaved. 



The 44 progeny (table 38) secured from the greenhouse single 

 mentionad above included 2 (4) narrow-dark-leaved individuals and 

 3 (5) other plants not Snowflake (the last including two smooth, one 

 large, one slender, and one semicrenate), besides five undetermined 

 plants. Plainly the type of the parent is still in doubt. 



