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



plication^\i\c\i we have called alternation of generations in animals, 

 must receive the same name here. The question, whether an 

 alternation of generations, according to the definition which we 

 have above given, is possible in the asexual multiplication of 

 plants which have attained the highest point of their development 

 (puberty) — a question which we first arrive at here, because no 

 case of this kind is known in the Animal Kingdom — must be 

 answered in the affirmative. But this is in such cases of course 

 only possible when the asexually produced progeny, which or- 

 dinarily directly repeats the development of its mother, has un- 

 dergone a retrogressive metamorphosis. We shall refer to this 

 again. 



The comparison of Phanerogamous plants with animals, as we 

 have attempted it in Table I., scarcely requires discussion. The 

 position of the developed animal as correspondent to the leafy 

 (and rooted) axis, whether this be simple or branched, is a direct 

 consequence of that conception of the individual which we have 

 declared for above. The comparison of the anthers with the 

 testis, of the ovule with the ovary, &c., bears reference of course 

 to morphological conditions. 



Very closely connected with the Phanerogamia as most strictly 

 defined, are the Gymnospermia (Cycadese and Coniferse), differing 

 from the former only in the internal structure of their ovules, 

 but through this very deviation forming the most direct and 

 easy transition to the groups of Belaginellce and Rhizocarpece. 

 Hofmeister* has already shown most strikingly that the essen- 

 tial parts of the ovule of the Coniferse, the secondary embryo- 

 sacs [corfuscula, R. Br.), correspond in every respect with those 

 of the archegonia, and, with their neighbouring structures — 

 epithelial appendage, covering-cells, — frequently imitate even 

 the form and structure of the archegonia. The only distinction 

 which can be found between the female organs of reproduction, 

 the essential parts of the female inflorescence of the two groups 

 of plants, is that in the Gymnospermia they remain in connexion 

 with the mother-plant until after fecundation is completed, 

 while in the Selaginellce and Rhizocarpea they separate from it 

 in a very early stage of their development, as rudimentary flowers 

 (megaspores). 



If we wish to call to mind further analogies within the repro- 

 ductive sphere of the two groups, we may mention the behaviour 

 of the pollen-grains on the one hand, and of the antheridial 

 grains (microspores) on the other, in both of which a long inter- 

 val of time intervenes between the morphological completion and 

 the accomplishment of their functional activity ; also the occur- 

 rence of a suspensor in Selaginella. 



* Vergleich. Untersuch. p. 140. 



