447
Orginal Articles.
XLVI.—Report on Vegetable Parthenogenesis.
The question as to the existence of parthenogenesis in vegetables has latterly been the subject of much discussion, but it is by no means of modern origin. It has been studied at different times by numerous botanists for pretty nearly 100 years, and after the lapse of a century the point in dispute seems as far from being decided as ever. In England the subject has attracted little attention, although the most important of all the apparent instances of parthenogenesis, that namely of Cœlebogyne ilicifolia, was first noticed in this country. A short time since it would have been a work of some labour to have given any readable account of the question at issue, but the difficulties in the way of doing so have been to a great extent removed by Dr. Regel's publication in the Memoirs of the Academy of St. Petersburg.[1] The latter author has given at some length the history of all the important observations preceding his own, and in the outset of the present report we wish to acknowledge the assistance we have derived from Dr. Regel's Memoir.
For some years prior to 1767 the observations of physiological botanists had been directed to prove the existence of sexes in plants, and we find the names of Grew, Camerarius, Linnæus, and Köhlreuter conspicuous amongst the writers upon this subject. In the year above mentioned (1767) we come upon the writings of Spallanzani, with whose experiments the question of parthenogenesis, as it exists at the present day, may be considered to have originated.
In May, 1777, Spallanzani selected two young female plants of hemp (Cannabis sativa), the sex of which was only just distinguishable. These were placed in a room facing the south, twenty days before their flowers opened, and kept enclosed between two window frames. As a further test, two of the flowering branches of one of the plants were enclosed in a glass flask, the mouth of which was hermetically sealed, and all the branches of the latter plant, with the exception of those in the flask, were cut off. The window frames were kept closed, and all the plants were carefully examined from time to time, without a single male organ being detected. After all these precautions the plants in question, and the particular branches enclosed in the flask, produced seeds, which afterwards germinated.
A second experiment was made, in which the female plants were brought into flower six weeks before the time of flowering of the hemp in the open fields, and similar results were obtained.
- ↑ Mémoires de l'Acaclémie Impériale des Sciences de St. Petersbourg, VII Série Tome I. No. 2.
