430 Dr. W. Hofmeister on the Fecundation of the Coniferse. 



the short sac-like part of the pollen-tube hangs, at this time, 

 in the summit of the corpusculurrij the body composed of four 

 cells, which is soon afterwards to be found at the bottom of the 

 corpusculunif that is to say, at the part opposite to the point 

 where the pollen-tube entered. This cellular body, out of which 

 are formed not only the so-called ' lower rosette/ but the sus- 

 pensors and the first cell of the embryo, makes its way very gra- 

 dually to the bottom of the corpusculum, detaching itself from 

 the sac-like portion of the pollen-tube. For the contents of the 

 corpusculum become very gradually more limpid from above 

 downwards ; the lower, denser portion, still filled with vacuoles, 

 consequently supports the cellular body, till at length it reaches 

 its goal and then undergoes further development. Not unfre- 

 quently, however, a division of the four cells in a horizontal 

 direction takes place earlier, on which account the cellular body 

 situated at the base of the corpusculum ordinarily consists no 

 longer of four simple cells arranged side by side in a rosette, but 

 of four double cells. I traced this cellular body both in its for- 

 mation from the end of the penetrating pollen-tube, and also in 

 its course downwards, so that I have seen it perfectly developed, 

 composed of four cells, still connected with the sac-like portion 

 of the pollen-tube, in the apex of the corpusculum, then in the 

 middle of the latter, and finally in the place of its destination^?^ 

 the base of the corpusculum (p. 326). i T 



'^ In the Yew {Taxus baccata) it is well known that the pollen- 

 tube applies itself as a large vesicle over the summit of the 

 embryo-sac ; it descends into the excavations under which the 

 corpuscula lie, and forms even there, before it has broken through 

 the softened wall of a corpusculumy in its interior (and apparently 

 by division, not by free cell-formation) a body composed of four 

 cells arranged like a rosette, which probably originates, like the 

 body composed of four similar cells on the pollen-tube of Pinus, 

 by the division of one mother-cell (whether by a single or two 

 successive divisions is a question). I was fortunate enough 

 several times to detach uninjured the pollen- tube overlying a 

 corpusculuMj so that I was enabled to examine the cellular body 

 lying in a pouch-like protrusion of the pollen-tube, most closely, 

 several times and on all sides. The apex, or rather the pouch of 

 the vesicularly expanded pollen-tube, in which the said cellular 

 body lies, in the next place sinks into the corpusculum, and gra- 

 dually fills it up by expanding until its size corresponds to the 

 cavity of the corpusculum. The cellular body situated in the 

 pouch of the pollen-tube, now inside the corpusculum, enlarges 

 meanwhile by repeated, but not always perfectly regular cell- 

 division * * *. I succeeded in dissecting out the portion of the 

 pollen-tube which had penetrated into the corpusculum, perfect, 



