1916] DEV RIES—DIMORPHIC MUTANTS 259 
limits of ordinary chance, although all the seeds from the 10 cap- 
sules of each group have been sown. Thus it is clear that the 
first and the last fruits of a spike and those of a side branch may 
give the same percentage figures of specimens of the parental 
type. Moreover, the mean value is not essentially different from 
the means of the pedigrees, as just given, which was 33 per cent. 
We may conclude, therefore, that bee mean percentage for all my 
annual cultures is about 30-40. 
In order to compare the influence of biennial culture upon this 
figure, I chose three healthy and very vigorous rosettes of 1913 and 
kept them through the winter under glass. They had been reared 
from seeds of a biennial mutant belonging to the group of cana 
mutants from Jata, from which pedigrees no. 2 and no. 3 were 
derived; but this special culture stayed in the rosette condition 
during 1913. In 1914 three plants of the cana type became very 
vigorous, reaching about double the height of the annual plants 
and growing up to more than 2.5m. ‘Their stems also had twice 
the thickness of the others, the foliage and flower spikes were very 
dense, and the flowers much stouter. Every evening 4 or 5 flowers 
opened on the same spike, against 1 or 2 in ordinary cases. The 
number of fruits on a spike was 60-80, whereas 40 fruits, as just 
given, is a high value for an annual plant. All of these fruits were 
self-pollinated in little bags, and yielded 1-1.3 cc. of seeds from 
10 fruits, whereas the annuals give only o.5-0.9 cc. of seeds in 
10 fruits. We may summarize these details by saying that my 
biennial specimens of 1914 were about twice as vigorous as the 
very best of all my annual cultures. 
TABLE IV 
Plant Fruits Seeds ince. | Seedlings P — of 
MOTs iets 63 6.6 590 96 
NO. 2.0. 79 10.0 1099 93 
INO. 35 oo 64 6.3 277 97 
All the seeds were sown in boxes in 1915 and the seedlings 
counted out, without being transplanted, in the stage correspond- 
ing to fig. 1, when the differentiating marks were very sharp. The 
three plants gave the results shown in table IV. 
