310 Remarks on the Impregnation of Plants. 



the pollen is supposed to be deposited in, and nourished by the ovule : 

 according to another, the germ is thought either to pre-exist in, or 

 to be originally formed by the ovule itself, and that it is merely exci- 

 ted into action by an influence derived from the pollen : and according 

 to a third, the embryo is conceived to result from the union of a germ 

 furnished by the pollen with another produced by the ovule.* It is 

 hardly probable that we shall ever possess the means of absolutely 

 proving the correctness or demonstrating the fallacy of either of these 

 hypotheses ; but it may be remarked that the first mentioned view, 

 which was advanced at an early period, is the most difficult to be 

 reconciled either with the phenomena of hybridity or with the man- 

 ifest analogy that exists between seeds and buds ; and yet recent 

 discoveries have again rendered it the more probable hypothesis. 



Soon after the discovery of the office of the pollen, several at- 

 tempts were made to explain the manner in which this substance 

 acts upon the stigma. Some of the earlier writers, such as Geoffiroi 

 and Malpighi, seem to take it for granted that the entire grains of 

 pollen which fall upon the stigma pass down the style quite into the 

 ovary ; and Morelandf suggested that the grains even penetrate the 

 ovules and become the embryo. The latter author, who was, I be- 

 lieve, the first to extend the hypothesis of Leeuwenhoek to the veg- 

 etable kingdom, inquires " whether it be not more proper to suppose 

 that the seeds which come up in their proper involucra, are at first 

 like unimpregnated ova of animals ; that this farina (pollen) is a 

 congeries of seminal plants, one of which must be conveyed into 

 every ovum before it can become prolific ; that the stylus in Mr. 

 Ray's language, the upper part of the pistillum in Mr. Tournefort's, 

 is a tube destined to convey these seminal plants into their nest in 

 the ova ; that there is so vast a provision made because of the odds 

 there are whether one of so many shall ever find its way into and 

 through so narrow a conveyance." He then proceeds to record 

 several circumstances ; which are, in his opinion, confirmatory of 

 this view ; especially the manifestly tubular style of the Crown Im- 



* The latter hypothesis is adopted by Ad. Brongniart with much confidence in 

 his memoir above cited. — " Dans cet espace . . . . un ou quelques-uns des granules 

 spermatiques s'unissent probablement k d'autres granules fournis par Fovule pour 

 donner naissance au petit globule, premier rudiment informe de I'embryo," &c. 

 Ad. Brongniart in Ann. Sci. Nat. 12, p. 254. 



t Some new Observations on the Parts and the Use of the flower in Plants ; by 

 Samuel, MoREr^AND. — Philosophical Transactions, Vol. 23, (1703.) 



