Meyen's Report for 1839 on Physiological Botany, 169 



actual fecundation, namely, on the conjunction of the pollen- 

 tube with the embryo-sac, and at the entrance of the pollen- 

 tube into the cavity of the nucleus. The greater part of these 

 observations is already published in the third part of my 

 ^ Physiology/ but here all the facts vrhich have reference to 

 this subject are arranged together, and indeed more clearly 

 than at first, for many points have become more evident to 

 me by continued observation. An eminent physiologist has 

 stated, that it appeared from my experiments that the embryo 

 w^as produced by the injection of the fovilla, or fertilizing 

 substance of the pollen-tube, into the embryo-sac, but 1 

 never had such a view of the act of fecundation of plants ; 

 and in the above-mentioned treatise the meaning of the 

 observations is explained more clearly. In some species of 

 Mesembryanthemum I have been able to observe the union 

 of the pollen-tube with the embryo-sac much more accurately 

 than before, particularly the curious lateral junction of the 

 apex of the pollen-tube with the side of the summit of the 

 embryo-sac in the case of M. pomeridianum. 



In consequence of this junction, in which the act of fecun- 

 dation consists, there is formed at the summit of the embiyo- 

 sac, directly under the point of junction, a little bladder, the 

 so-called germinal vesicle (Keimblaschen), from which the 

 suspensor and the embryo-bladder are produced, which is 

 described and delineated. I never saw a larger embryo-sac 

 than in this Mesembryanthemum, in which the ovulum is 

 half curved, and is twisted back by a bend in the umbilical 

 cord. In the case of M, linguceforme, the junction of the 

 pollen-tube with the embryo-sac takes place exactly at the 

 extremity ; and after the germ-bladder is formed, the end of 

 the pollen-tube enlarges considerably, and remains so for a 

 very long time ; while in perfectly similar species the pollen- 

 tube disappears directly after fertilization, etc. 



M. Decaisne* has laid before the Academy of Paris a very 

 interesting research on the development and structure of the 

 flowers of Viscum album, and MM. Mirbel, Jussieu, and Ad. 

 Brongniart have given a report of the results, of which we 

 can here mention only the most important. 



The cells of the anthers and of the calyx-leaves, with 

 which the former are grown together, do not exhibit in their 

 form any difference, except that the latter are filled with a 

 green substance, whereas the former are colourless. Five 



* Devclopeinent du pollen clans le Oui ; changemens que pr^sentent ses 

 ovules ct ceux du Thesiuni. — Coniptes Rcndus do 1839, 11 Fevrier, p. 201. 

 — [Translated in the Annals of Natural History for May 1841, p. 185. — Ed.] 



