156 THE JOURNAL OF BOTANY 



described as taking place in the species of violet belonging to the 

 Melanium section. In the summer, however, special branches of 

 the same individual plant bring forth small green flower-buds 

 which do not open, but nevertheless produce soon afterwards large 

 ripe capsules full of seed. This phenomenon, in apparent contra- 

 diction to the ordinary idea of the result of the flowering process, 

 did not escape the attention of the botanists of the eighteenth 

 century, and they named this species of violet in which the majority 

 of the large open blossoms fail to produce fruit whilst the closed 

 bud-like flowers are invariably productive Viola mirabilis, or ' the 

 Wonderful Violet.' In V. mirabilis and in all its allied species, 

 called i caulescent ' in the language of descriptive botany, the 

 cleistogamous flowers are developed on special shoots, and these 

 shoots are either erect or else prostrate in long zigzags. . . . • 

 In several violets of the kind called by descriptive botanists 

 1 acaulescent,' such as V. collina and V. sepincola, the cleistogamous 

 flowers develop likewise underground, their stalks springing from 

 special shoots of the rootstock. In all these cases the two kinds of 

 flowers are always borne on the same plant, though on different 

 branch systems. . . . There is a species of violet named V. 

 sepincola which grows deep in the shade of the woods clothing the 

 hills at the foot of the Solstein chain in the Innthal district. I 

 saw it there for the first time about the middle of May, and it was 

 then covered with an abundance of ripe fruit. In following years 

 I looked for flowers of this plant early in the spring, as soon as the 

 snow had melted, but found that not a single individual had deve- 

 loped open flowers with expanded petals on erect above-ground 

 stalks. On the other hand, there were a number of cleistogamous 

 flowers concealed under the fallen leaves and partially buried in 

 the earth, so that it looked very much as if the species produced no 

 other kind of blossom. But plants subsequently reared in a part 

 of my garden which was exposed to the sun's rays during some 

 hours of each day developed, in the next year but one after their 

 being sown, in addition to cleistogamous flowers, beautiful scented 

 blossoms of a violet colour, which were borne on erect stalks, and 

 in due time unfolded their petals. This result throws some light 

 on the nature of the stimulus which causes the formation of the 

 flowers in question. No open aerial flowers were produced by 

 V. sepincola so long as it grew in the cool shade of a dense wood, 

 but when transferred to open ground accessible to sunlight, such 

 flowers were developed. One can hardly err in ascribing to the 

 sun's rays a very important influence in stimulating plants to the 

 inception of flowering-shoots, especially such as bear blossoms 

 possessing bright-coloured petals. Indirectly, however, this advan- 

 tage accrues to the plants in question that, living as they do in 

 deep shade, where no bees would, in any case, visit them, even if 

 they had open flowers, they can confine their constructive energy 

 to the inception and development of cleistogamous flowers and save 

 themselves the trouble of producing open flowers adapted to cross- 

 fertilization (but useless in the place in question). If the spot 

 where the violet grows becomes exposed to the sunlight through 



