1885.] NEW-YORK MICROSCOPICAL SOCIETY. 15 



Sachs describes the fertilization of the Coniferce as follows, 

 giving illustrations of Taxus Canadensis a,nd Juniperus co??imunis, 

 both taken from Hofmeister : — ^* 



" The pollen-grains having reached the apex of the nucellus 

 put out their tubes at first only for a short distance into its tis- 

 sue ; their growth is then for a time suspended. After the arche- 

 gonia are completely developed, the pollen-tubes begin to grow 

 again into the endosperm in order to reach them."'' * * * * 

 Whilst the pollen-tubes penetrate through the loose portion of 

 the tissue of the nucellus, their width gradually increases at their 

 lower end, their wall becoming at the same time thicker ; until 

 at length they meet the wall of the embryo-sac which has now 

 become soft, break through it, penetrate into the funnel of the 

 endosperm, and attach themselves firmly to the cells of the neck 

 of the archegonia." 



The process in Angiosperm^ is thus described, and a figure 

 of the fertilized ovule of Viola tricolor given in explanation: — ^* 



" The pollen-grains which germinate on the stigma send out 

 their tubes through the channel of the style where there is one, 

 or more usually through the loose conducting tissue in its interi- 

 or, down to the cavity of the ovary. Frequently both in erect 

 basilar and in pendulous anatropous ovules the micropyle lies so 

 close to the base of the style that the descending pollen-tubes 

 can enter it at once ; but more often the pollen-tubes have to 

 undergo further growth after their entrance into the cavity of 

 the ovary before they reach the micropyles of the ovules ; and 

 they are then guided in the right direction by various contrivan- 

 ces.^" * * * * Since every ovule requires one pollen- 

 tube for its fertilization, the number of tubes which enter the 

 ovary depends, speaking generally, on the number of ovules con- 

 tained in it ; the number of pollen-tubes is, however, usually 

 larger than that of the ovules ; where these latter are very nume- 

 rous, the number of pollen-tubes is also very large, as in Or- 

 chidese, where they may be detected in the ovary even by the 

 naked eye as a shiny white silky bundle." 



28" Text Book of Botany," Edited by Sidney H. Vines, Oxford. 1882, pp. 523, 524. 



2 'Compare Detmer, loc. eit. "In Salishuria adfawif/oZia (Ginkgo), fertilization 

 does not take place till October, when the fruit is ripe and has already fallen off. The 

 embryo is developed within the seed during the winter months " (See Strasburger 

 " Die Coniferen und Gnetaceen," 1872, p. 291). 



28L0C. cit., pp. 582, 583. 



"^Compare Detmer, " Jenaische Zeitschr. Naturwiss." XIV., p. 530. 



