IN THE VEGETABLE KINGDOM. 63 



tion of the sac, and the formation of the embryo from a 

 process of cell-formation in the extremity of the pollen 

 tube, while other botanists of note did not admit more than 

 an intimate contact between the extremity of the tube and 

 that of the embryo-sac. 



The controversy may be said to be now mere matter of 

 history, the former view having latterly been abandoned by 

 its most distinguished supporters Tulasne, Schleiden, and 

 Schacht.* It seems to have arisen from the suspensor of 

 the embryo having been mistaken for, or confounded with, 

 the extremity of the pollen-tube. As it would appear, 

 therefore, that there is no perforation either of the embryo- 

 sac or of the pollen-tube, such commixture of their con- 

 tents, as may be necessary for impregnation, must be held 

 to depend on the transudation of the fovilla through the 

 interposed membranes into the sac, in which it is now ge- 

 nerally admitted that the embryo is developed, out of one of 

 the contained "germinal vesicles." Impregnation through 

 interposed membranes is certainly not according to the ge- 

 neral analogy of the reproductive process, but it were prema- 

 ture to assert that it does not occur in other divisions of 

 organic nature.f The " germinal vesicle" which has under- 

 gone impregnation becomes resolved, as in the Coniferse, 

 into two cells, the upper forming the confervoid suspensor, 

 the lower the embryo. { The latter is at first a globular 

 mass of cells, but generally, while the seed is ripening, cer- 



* Henfrey Annals Nat. Hist., 2d Ser., XVII., 313. 



f In Dr. Carter's Observations on CEdogonium, before noticed, (ch. II., 

 4), no bodily penetration of the antherozoids was visible. They 

 seemed to degenerate into drops of reddish mucilage on the mucus-layer 

 of the sporangium, and to be absorbed by a sort of endosmose. Annals 

 of Nat. Hist., 2d Ser., XVIII., 81. 



$ In the phanerogamic ovule, the suspensor is generally formed after 

 the development has commenced of the proper embryo ; its prior forma- 

 tion in the Coniferae is one of the points in which this group presents a 

 transition to the characters of the Cryptogamia. 



