1899.] NATURAL SCIENCES OF PHILADELPHIA. 97 



It would seem from these observations that the glaud in Isnardict, 

 palustris is really stipular; that the petals are not abortive, but 

 have beeu covered by the connation of the sepals; that the flowers 

 are arranged so that self-fertilization must ensue; that these self- 

 fertilized flowers are enormously productive; and that the produc- 

 tion of nectar, so far as the visits of insects may be concerned, is 

 superfluous. 



VII. Parthenogenesis. 



It is about two hundred years ago since Camerarius recorded 

 the fact that female mulberries and other trees would produce fruit 

 without pollinization, though such fruit was sterile. These obser- 

 vations have since beeu abundantly confirmed. The necessity of 

 pollen to fertile seed came to be regarded as absolute law, until 

 some fifty years ago, when the Curator at Kew, Mr. John Smith, an- 

 nounced that an Australian plant, of which he had but one female 

 specimen, perfected its seeds. It proved to be a new Euphorbiaceie, 

 and he named it Ciclehocjyne ilicifolla — the generic name from its 

 supposed parthenogenetal character. 



The author of this paper was a student in Kew at that time, and 

 well remembers the incredulity with which the announcement Avas 

 received, that nature should seem to make a universal law in rela- 

 tion to method of reproduction, and yet make a striking exception 

 in this case. Nature furnishes infinite variation, but these varia- 

 tions seem to be only of one general plan. It seemed more prob- 

 able that, in some method unexplained, pollen had been formed, 

 and really pollinated the embryo. It does not appear that any 

 further observations on this plant were made at Kew, or, if made, 

 recorded. 



Strasburger took up the subject again in 1878, but though my 

 good friend, j\Ir. George Nicholson, Curator of Kew, writes under 

 date of April 10, 1897, that " the whole business has been 

 threshed out by Strasburger," the latter seems to be more concerned 

 about the cell development than the manner of its fertilization. 

 This is especially true of that part devoted to the Castor-oil plant, 

 Ricinus com munis. In Ccdehocjyne, he insists that the true embryo 

 does not develop, but that the seeds proceed from adventitious 

 buds from the wall of the ovary. One may conceive of them as 

 bulblets, analogous to what we find in viviparous flowers; but he 

 7 



