8 JOURNAL OF THE [January, 



but the revival of an ancient supposition ; and this fact suggests 

 that a series of extracts from the works of investigators of ac- 

 knowledged ability, which shall illustrate the growth of the 

 accepted theory from its birth, will materially aid my effort to 

 show that Mr. Kruttschnitt's position is untenable. 



Until the observations of Amici (1823), pollen-tubes remained 

 undiscovered, though the influence of pollen in seed production 

 had long been recognized. "It was at first thought that the 

 grains of pollen simply open on the stigma, and that the granules 

 which they contain, being absorbed by the stigma, go to form 

 the embryo, or concur in its formation."'* Amici noticed the 

 tubes proceeding from the pollen of Portulaca oleracea, and that 

 they are formed by the protrusion of the intine through the ex- 

 tine.^ A few years later Adolphe Brongniart examined the pol- 

 len of numerous species of plants and observed the tubes ; he 

 succeeded in following them only into the style, where he be- 

 lieved they terminated and discharged their contents.*^ At about 

 the same period, Amici and, independently, Ehrenberg made 

 observations indicating similar results. In 1831 Robert Brown 

 presented to the Linnasan Society of London his memoir on 

 "The Organs and Mode of Fecundation in the Orchideas and 

 Asclepiadeae ;"' at that time he had traced the pollen-tubes to 

 the placentae, and possibly in one instance to the ovule. 



In a subsequent communication to the Linntean Society, 

 " Additional Observations on the Mode of Fecundation in Or- 

 chideae,"* speaking of pollen-tubes, he says : 



" In Orchis Morio I have repeatedly and very clearly observed 

 them scattered in every part of the surface of the placenta, and 

 in not a few cases have been able to trace them into the aperture 

 of the ovulum, to which they adhere with considerable firmness ;" 

 and in a foot-note he adds, "Since these additional observations 

 were read, I have found in several other Orchidece, especially 

 Habcnaria viridis and Op/irys apifera, tubes scattered over the 

 surface of the placenta, and not unfrequently inserted in like 

 manner into the apertures of the ovula. * * * * At what 

 l)eriod they reach the foramen of the testa, whether before or 



4Figuier, " The Vegetable World," p. 179. 



5 Atti della Societa Italiaua, Vol. XIX., p. 251, aud Ann. Sci. Nat., Vol. n., p. GO. 

 cAun. Sci. Nat., Vol. XII., p. 31. 

 'Trans. Linn. Soc. Vol. XVI., pp. (!S,")-7-j.'). 



■* Head June 5tli, 1832; see "Miscellaneous Botanical Works of Robert Brown," 

 published for the Kay Society, London, l«G6, p. 540. 



