on Mercurialis were conducted in a similar manner and with similar results. The Bryonia was kept in a room in the Museum at Paris, entirely isolated from all male plants, and yet for three years successively it produced a few perfect seeds. A young plant raised from one of these seeds also produced perfect seeds without apparent impregnation, and the number of them when counted, was found to be about the same as that produced by a female plant exposed to the influence of pollen. This result M. Naudin considers to be opposed to the supposition of impregnation by the aid of insects, which however he thinks may possibly have been the case with the Bryonia.
The plants of Ricinus and Ecbalium produced no perfect fruit, and M. Naudin is of opinion that diæcious plants are more apt to produce fruit without impregnation than monæcious ones. In 1857, Radlkofer published some remarks upon the present subject in Siebold and Kölliker's "Zeitschrift fur. wiss. Zoologie." He assumes the certainty of the absence of male organs in the female plants of Cœlebogyne. He examined the young embryo-sacs, in which he found three germinal vesicles, of which sometimes one, sometimes two, or even all three, became true embryos. He concludes that a true parthenogenesis exists in Cœlebogyne; and he considers this conclusion fortified by the fact (previously noticed by Smith) that the stigma remains fresh until just before the ripening of the seeds, whilst in ordinary cases it withers shortly after impregnation. He states that, although the stigma in Hemp and in Mercurialis withers soon after impregnation, he had noticed its persistence in one of the female Hemp plants experimented upon by Naudin, and in a female plant of Mercurialis annua which had been kept by M. Thuret apart from the male.
Braun's elaborate essay on parthenogenesis appeared in 1857 in the "Transactions of the Berlin Academy." After referring to the accounts of previous observers, which, before Cœlebogyne was known, had rendered the existence of parthenogenesis probable, he states that the latter plant is one which fulfils the necessary conditions. The observations made at Berlin agreed with those at Kew, as to the fact of the production by female plants of perfect seeds without any process of impregnation. He considers it to be against all probability that any abnormal mode of impregnation, as by the glands, observed by Smith, should exist, and notices in detail some observations made at his request by M. Deecke, as to the mode of origin of the embryo in Cœlebogyne, the result of which was to show that the process differed in no way from ordinary embryo-formation as observed by Hofmeister, Tulasne, and Radlkofer. After noticing that Radlkofer's observations differed from Deecke's only in the fact that the former found three and the latter only two embryonic vesicles, Dr. Braun remarks, "These observations lead to the result, that in "Cœlebogyne the germs of new individuals are developed within a normally constructed female organ of generation without any
