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(Original $rttrtcs. 



XLYI. — Eepokt on Vegetable Paethexogexesis. 



The question as to the existence of parthenogenesis in vegetables 



has latterly been the subject of much discussion, tnit it is by no 

 means of modern origin. It has been studied at different times by 

 numerous botanists ibr pretty nearly 100 years, and after the lapse 

 of a century the point in dispute seems as far from being decided as 

 ever. Li England the subject has attracted little attention, although 

 the most important of all the apparent instances of parthenogenesis, 

 that namely of Ccelebogync i/icifolia, 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 difficul- 

 ties in the way of doing so have been to a great extent removed by 

 Dr. Hegel's publication in the Memoirs of the Academy of St. Peters- 

 burg.* 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. Eegel's Memoir. 



Tor 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, Linnaeus, and Kohlreu- 

 ter 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. 



* Memoirea de 1'Acaclemie Imperiale rtcs Sciences do St. Petersbourg, VII' 

 Seric Tome I. No. 2. 



VOL. I. — TSf. IT. E. 3 U 



