454 Scientific Proceedings, Royal Dublin Society. 



All these modes of non-sexual generation which cannot be 

 included under the head of sporogenesis I would distinguish as 

 blastogenesis, and the special reproductive bodies as blastidules. 

 These blastidules are very varied, and appear as conidia, propa- 

 gula, gemmae, buds, or even as fragments of a large plant. 



The reproduction of plants is thus of two kinds : — 1, gamo- 

 ' genesis, or sexual reproduction ; and 2, agamogenesis, or non- 

 sexual reproduction. Agamogenesis appears under two forms — 

 namely, sporogenesis and blastogenesis, and when there is meta- 

 genesis, or alternation of generations, it is an alternation of gamo- 

 genesis and sporogenesis. Blastogenesis may occur both in the 

 sporophore and gametophore stage, and numerous examples might 

 be given. Then gamogenesis may be absent, and the plant may 

 reproduce by sporogenesis or by blastogenesis, as in most Fungi. 



Lastly, as we have in such forms as Ulothrix and others mul- 

 tiplication sometimes by gamogenesis, sometimes by agamogenesis, 

 the sexual cells which have failed to form zygotes often developing 

 by themselves non-sexually, thus giving us intermediate forms 

 between sexual cells and spores ; so we may expect to find that 

 there are intermediates between spores and blastidules. 



