360 Dr. L. Radlkofer on Fecundation in the Vegetable Kingdom, 



away from the micropyle, where it first of all becomes divided 

 by a cross-septum. Sometimes in both daughter-cells, some- 

 times in one only, there occurs a division by two vertical septa 

 standing at right angles, forming the so-called lower cell-rosette, 

 the pro-embryo (Hofmeister) . After further cross-division once 

 or several times repeated (and longitudinal division in some 

 Coniferse), the pro-embryo comes to consist of a few (3-4) super- 

 posed stories, each of 4-6 cells, the second or first of which 

 (counting av/ay from the micropyle) elongates greatly, breaks 

 through the base of the corpusculum, and penetrates into the 

 disintegrated endosperm, pushing onward the lower tiers of cells 

 before it. 



In the further behaviour of this pro-embryOy usually composed 

 of four strings of cells, lies the second of the deviations indicated 

 above ; to wit, the individual strings of cells of which it is com- 

 posed separate from each other gradually, from below upwards 

 (in Taxus only imperfectly), and the end-cell of each string pro- 

 duces a rudimentary embryo of some size ; but only one of all 

 those contained in the ovule proceeds further in its develop- 

 ment, all the rest becoming abortive. Some observers, especially 

 Geleznoff, question the subdivision of the pro-embryo into single 

 suspensotrs*. 



So far as existing researches can show, the Cycadeee agree 

 with the Coniferse in the organization of the ovule and the 

 formation of the embryo. 



MoNocoTYLEDONEs and Dicotyledon Es (Phanerogamia in 

 the restricted sense). — In these plants, one (rarely more) of the 

 two or more cells lying in the apex of the embryo-sac — the ger- 

 minal vesicles, — is, through the influence of the pollen- tube, which 

 ordinarily applies itself upon the outside of the embryo-sac, more 

 rarely breaks through it, and allows a part of its contents to 

 exude, enabled, by elongation and one or several times repeated 

 cross-division, to change into a one- or many-celled pro-embryo, 

 the end-cell of which, by repeated division in different directions, 

 produces the embryo-mass, the embryonal globule. This consti- 

 tutes the rudiment of the first, developing axis of the new plant, 

 the lower end of which, turned toward the micropyle, becomes 

 the root, while, by the sprouting of the first leaves below its 

 point, the upper end becomes the terminal bud. 



For the literature and the evidence of the statements made in 

 the text, I refer the reader to my recently published memoir ' Die 

 Befruchtung der Kryptogamen,' Leipsic, 1850. To the literature 

 cited in the historical part of that essay — in which it was only in- 

 tended to touch upon what was of especial importance for the deve- 



* Gottsche, Botan. Zeitung, 1845, p. 3/8 et seq. 



