34 Linncean Society. 



archegonia, with their papillae and embryo-sacs ; and fourthly, he 

 gives his own view of the development of the embryo. On all these 

 points he enters into much detail, tracing the several stages of the 

 process with great minuteness. In bis criticism of previous obser- 

 vations, he passes in review the facts and opinions stated by Nageli, 

 Suminski, Wigand, Thuret, Hofmeister, Schacht, Mettenius, Von 

 Mercklin, and Hofmeister again ; and indicates the points in which 

 they severally differ from each other, and also those in which he 

 himself either coincides with or differs from each of them. The 

 memoir is so completely one of detail, that under these two principal 

 divisions it would be difficult to give a sufficiently clear abstract 

 without running to too great a length ; and this is the less necessary 

 as the memoir itself will immediately appear in full in the Society's 

 ' Transactions.' 



Under the head of " Development of the embryo " the author 

 gives the following statement of his opinion on the question of 

 impregnation, and the mode in which it is effected : — " My opinion 

 with regard to the fertilization is, that the operation is effected 

 by the contact of one or more spermatozoids with the mucilaginous 

 filament contained in or hanging from the mouth of the canal of 

 the archegoniuvi. I have seen the spermatozoids swimming iu num- 

 bers around the mouths of archegonia, but never detected one inside, 

 and I do not see any good reason for supposing such a process 

 necessary. The pollen-tube of flowering plants only comes in con- 

 tact with the outside of the embryo-sac, and the influence is some- 

 times communicated through a long suspensor ; and there does not 

 seem to be any suflicient objection to the supposition, that the 

 contact of the spermatozoid with the filament of mucilage which lies 

 in the canal of the archegonium, suffices to convey the necessary sti- 

 mulus. I imagine this stimulus resides.in the mucilaginous fluid in 

 which the spermatozoid is bathed in the sperm-cell, and which, ad- 

 hering to this, is conveyed to the mucilage (protoplasm) of the ger- 

 minal vesicle, just as the contents of the pollen-grain become com- 

 bined with the protoplasm of the germinal vesicle in flowering 

 plants. The nature of the process is clearly a problem beyond the 

 reach of science, but it seems to me a necessary induction from the 

 facts in the Phanerogamia, that the phsenomena result there from the 

 material union of two fluids, and I hence conclude that this is the 

 case here. The comparatively few cases of successful impregnation 

 among these prothallia, so many of which prove sterile, may perhaps 

 be accounted for by the peculiar conjunction of circumstances re- 

 quired to bring a sufficient amount of the fertilizing fluid, by means 

 of the spermatozoids, to the germinal vesicle, at the precise epoch 

 required." 



His general " conclusions " are as follows : — " In summing up 

 all these statements it becomes evident that the balance of evi- 

 dence is in favour of the existence of sexual organs, and of a process 

 of impregnation, giving rise to a new individual, as asserted by 

 Suminski, although under conditions somewhat different from those 

 described by that author. Only two of the observers who have re- 



