438 MR. A. W. BENNETT ON THE 
and others, occupy the whole of the connecting tube; and the 
portion of the tube which it occupies is never its centre, except that, 
where the conjugating filaments lie close together, the tube is so 
short as to be entirely filled by the zygospore. Otherwise it 
appears to be always nearer to one end than the other (fig. 6); 
and a certain amount of differentiation is indicated by the fact 
that when a number of zygospores are formed between two con- 
jugating filaments, the whole of them are nearer to one filament 
and further from the other (fig. 7). This I observed in several 
eases where as many as seven or eight pairs of cells were conju- 
gating. If we follow out by analogy the physiologieal value of 
the two cells assumed in the case of Spirogyra and Zygnema, 
we may suppose that we have here a still more rudimentary dif- 
ferentiation of the male and female elements, the differences 
between the forces being too small to result in the complete 
passage of the male element into the female cell. The filament 
nearest to which the zygospores are formed must here be regarded 
as the female; that which puts out the longer protuberances as 
the male filament. It became then of interest to determine 
whether there was here again any difference in size between the 
cells of the male and female filaments. And here a very un- 
expected circumstance was revealed. In the diameter of the two 
filaments I could detect no difference whatever. It is given by 
Cooke as ‘034 mm., which may be regarded as a fair average. 
But in the length of the cells there was a distinct difference— 
the average of that of the male cells being about ‘11, of the 
female cells about -085, the very singular phenomenon being exhi- 
bited of the femae cells being smaller, instead of larger than the 
male cells. 
Staurospermum gracillimum, Hass. Two filaments in conjugation. X 165. 
In Staurospermum (fig. 8), where the zygospore is formed by 
