West & West. — Observations on the Conjugatae. 39 
stimulus which has already caused conjugation to take place 
in a distant part of the filament. 
Indications of sexuality are to be found in the Mesocarpeae, 
but they are much less marked than in the Zygnemeae. The 
spores are often seen to be nearer one filament, and the 
conjugating-tubes of that filament to be thicker and shorter 
than those of the other (cf. Fig. 47) ; hence the former may 
be looked upon as a female and the latter as a male filament 
As these scarcely appreciable indications of sexuality are 
often absent, we may regard the Mesocarpeae as having lost 
almost all traces of differentiation into male and female 
gametes. 
1 . Gonatonema. The sterile specimens of this genus are 
undistinguishable from those of Mougeotia , although the 
chromatophore is more an axile rod (as in Mougeotia capucina ) 
than an axile plate ; the species of this genus are also of 
very much rarer occurrence than those of Mougeotia. The 
spores are asexual and parthenogenetic, and the whole con- 
tents of the cell are utilized in their formation. 
During the formation of the spore and just before the 
appearance of the thin membrane round the cell-contents, 
we have noticed, both in G. Boodlei and G. tropicum , that 
in a few of the cells a more or less indistinct division of the 
cell-contents into two portions takes place. As to the 
precise import of this we cannot at present offer an opinion. 
Is it merely a chance arrangement of the cell-contents, or 
may it not be some slight retention of the last traces of 
ancestral sexual characters ? Much is yet to be observed from 
the study of living Gonatonema during the active formation 
of spores. 
It is also noticeable that the great difference in size 
between the spores of G. Boodlei and G. tropicum is more 
than can be accounted for by the difference in cubical 
capacity of the vegetative cells and contained cell-contents, 
the latter being almost the same in each case. 
Figs, 1-15 illustrate the spore-formation in two species of 
Gonatonema which as yet have not been figured. 
