14 PROCEEDINGS OF THE 



to be found is that of the well-kuown (Edogonium ciliatu/m. 

 During the time of its active vegetative growth the series 

 I of cells of this Alga, which are of considerable dimensions, are 



/ green from the presence of chlorophyll. At this time the fila- 



ments increase in number by ciliated zoospores, each formed by 

 the entire contents of one of the cells. As the conditions become 

 less favourable for vegetative activity, the zoospores give origin 

 to two forms of filaments ; of these one is distinguished by its 

 small diameter, the shortness of its constituent cells, and the 

 yellow colour presented by its endochrome. The protoplasm of 

 certain of the cells divides into two, each becoming ciliated, con- 

 stituting androspores. AVe have in these filaments the assump- 

 tion, to a certain extent, of male characters. Besides these, 

 there are others which in general appearance closely resemble 

 the last described, but which, instead of forming zoospores, 

 possess certain cells which increase in dimension : such cells con- 

 stitute oospores. Near the future orifice of these cells one of 

 the androspores settles, and grows into a minute male filament 

 ot' three cells only ; the protoplasm of the larger of the three cells 

 breaks up into antherozoids, on the further development of which 

 it is perhaps not necessary to dwell. 



The noticeable points of this case are the assumption of sexual 

 . characters on the approach of adverse conditions ; the small size, 

 and relative absence of chlorophyll, in the male ; and the posses- 

 sion of normal secondary sexual male features by the asexual 

 filament which produces the androspores. 



If we now turn to the higher Algfe, '• Carposporae," we find a 

 good example in CaJlojpliyUis lacinkita, for an opportunity of 

 examining which 1 am indebted to Mr. E. M. Holmes. We 

 shall see that the male is relatively small and pale in colour, with 

 the sexual organs, the antheridia, along the borders of the thallus. 

 The male is exceediugh^ rare ; the female is much larger and 

 altogether more robust in texture, thicker, and much deeper in 

 colour. 



Among the Hepaticse we have Metzgeriopsis pusilla, where we 

 find the thallus producing at certain points male, and at others 

 female branches. If we examine the male branch, the leaflets 

 will be found relatively small, and bearing antherozoids on the 

 surface facing the stem ; in the female branches, however, the 

 leaflets are larger, Avith their margins often produced into spine- 

 like points, and with archegonia near theii- bases, gemmae being 

 often found at various points near their margin. All the features, 

 then, of the female branches show greater vigour. 



In the higher mosses, Mnium ajffine has the male branches of a 

 paler colour, from their possessing less chlorophyll and fewer 

 leaves than the female ; the latter is more robust, has more 

 closely crowded leaves, which are darker in tint and form con- 

 spicuous tufts at the free end. Much the same characters are 

 presented by Leucohryum glaucum, Dicranum scoparium, &c. In 



