EXPLANATION OF THE PLATES. 



Plate L — Reproduction in ALOiE and Fungi. 



Figs. 1 and 2. —Filamentous Algae in conjugation, (p. 23) after 

 Smith. In Fig. 1, ( ATesocarjms, ) the endoohrome of both the 

 conjugating cells is evacuated into the comiecting tube formed 

 by the fusion of their papillary outgrowi^hs, and tlie spore i» 

 matured in the same place ; in Fig. 2, only one of the conjugat- 

 ing cells evacuates its contents, which are received into the 

 other, where the spore is formed from the fusion of the two 

 endochromes. In this figure conjugation is sliown between the 

 ceUs of distinct filaments, as well as between two adjoining cells 

 of the same filament — a circumstance showing, j\s Mr. Smith 

 remarks (Trans. Microsc. Soc, II. 70), that the importance of 

 variations in this respect, as distinctive characters, has been 

 over-rated by some NaturaHsts. 



Fig. 3 (from RaKs) shows the process of conjugation in the 

 Desmidieee (Clostermm acerosum). The evacuation of the cells 

 takes place by the separation of their valves, and the spore is 

 formed, as in Mesocarpus, midway between the cells. 



Fig. 4 (also from Ralfs) represents a process of endogenous 

 multiplication in the germination of the spore of ClosUrium 



(p. 27). 



Figs. 5 and 6 (Eunotia turgida, from Thwaites), ilhistrato the 

 process of conjugation in the Diatomacea?, in wliich the effused 

 endochromes are resolved either at once, or at a very early 

 l>eriod, into two spore-masses, which are ultimately trans- 

 formed into frustules of a much larger size than their i)ari^uts. 

 The genetic cycle is supposed to be completed l>y their breaking 

 up into frustules, Uke those originally concerned in the process 



of conjugation (p. 28). 







