A Contribution to the Life-history of Viola 
BY 
MARY C. BLISS. 
With Plates XVII-XIX. 
Introduction and Methods. 
HE present study is based upon an investigation of the chasmogamic 
X flowers of Viola o dor at a , Viola pedata , Viola fimbriatula , Viola 
cucullata , and Viola pubescens. Of these V. cucullata and V. pedata were 
found to be the most favourable species for study. The ovules are larger 
than in the other species, and the structures of the embryo-sac are less 
difficult to determine. The cleistogamous flowers were studied only by way 
of comparison, and offered no interesting differences as regards the develop- 
ment of the embryo-sac up to the eight-nucleate stage. Beyond this stage, 
the development of the female gametophyte in these flowers was not 
observed. Material has been collected for a comparative study of the floral 
parts of the cleistogamic and chasmogamic flowers, and it is my purpose to 
determine, if possible, the causes and conditions which operate to produce 
the cleistogamic flowers or which tend to modify the structure of the chasmo- 
gamic flower. It is interesting to note that violet plants transplanted from 
the open to the greenhouse in early spring produced only a few chasmo- 
gamic flowers and many cleistogamous flowers, but often transitional forms 
were developed, cleistogamous flowers with rudimentary petals and with 
more than the usual two stamens. The details of these phenomena will be 
considered in a later paper. 
The material for this present work was collected in Wellesley and 
Needham from March io to May 27, 1903, and in Philadelphia from 
March 25 to May 1, 1908, Long before the first signs of leaves appeared 
in most of the species, V. odorata was in bud. The buds of the other 
species appeared in the following order : V. fimbriatula , V. cucullata , 
V. pedata , and V. pubescens . Buds of various sizes were collected and 
classified under the following heads : smallest buds, colourless, embedded in 
the crown of the root-stock ; buds green, medium ; buds larger, but still 
wholly green ; buds with corolla visible; buds just opening and buds half 
[Annals of Botany, Vol. XXVI. No. Cl. January, igis.] 
