452 i)r. L. Radlkofer on Fecundation in the Vegetable Kingdom, 



flower the totality of the organs necessary for fecundation, or 

 of these together with their immediate suppoi-t and special en- 

 velope when this is present, we may apply the term to the pro- 

 thallium bearing antheridia and archegonia, as was done by 

 Suniinski, the discoverer of the fecundating process of the Ferns ; 

 and it may be regarded only as an inessential peculiarity that 

 here this does not attain its perfect development in connexion 

 with the plant which produces it, but separates from the latter 

 in its most rudimentary condition, — we may say, as the first cell 

 of the floiver-bud. 



In the jMosses we find archegonia and antheridia both again 

 developed and their functions completed in connexion with the 

 plant morphologically perfect and arrived at puberty. But from 

 the fertilized germinal vesicle is not produced, as in thePhanero- 

 gamia and Ferns (in the widest sense of both terms), an embryo, 

 which — either as primary or secondary axis — grows up, after a 

 period of rest in the former, and immediately in the Ferns, into 

 a plant like the mother ; it gives rise to a structure totally dis- 

 similar from the mother-plant, remaining mechanically connected 

 with this, finally, by the production of numerous gonidia (spores) 

 in its interior, which do not give birth to a like progeny, dis- 

 playing the chai-acter of a genuine nurse (Amme). Its progeny 

 even (of the first generation) do not — in the jMosscs, at least — 

 regain the type of the sexual plant ; they represent rather a 

 second generation of nurses — protonema, — each of which produces 

 a renewed asexual propagation by the formation of buds. It is 

 the individuals originating in this way that assume the power of 

 growing up into sexually- potent plants. 



In here agreeing w^ith Henfrey* in regarding the protonema 

 (pro-embryo) of Mosses as a nurse, in opposition to Hofmeistei-^st 

 opinion, 1 consider it less necessary to justify myself, since in so 

 doing I remain true to the above-given well-established concep- 

 tion of the alternation of generations, than to endeavour to 

 remove the obstacles for those who might find an objection 

 in the difiiculty which seems to be produced by the occur- 

 rence of a similarly formed pro-embryo in the asexual multipli- 

 cation of full-grown JMosses, on their radical hairs, cells of the 

 leaves, &c. We have discussed above the question whether an 

 alternation of generations is possible in the asexual multiplica- 

 tion of perfectly developed organisms, i. e. whether with the 

 asexual multiplication of such can be combined a metamorphosis 

 terminating in the restoration of the mother-type. Such a com- 

 bination involves, of course, a previous retrogression to a lower 

 stage of development. This is given when the cell of the full- 



* Report Brit. Association for 1851, p. 121, note, 

 t Flora. 1852, |). 6. 



