NOTICES OF Books, 8738 
oh ‘oad ies are andros osporous—one only as yet observed, B. poly- 
andra, Cleve, ete Saitek osporous. 
The oogonia of both the genera before fecundation present an 
opening in the membrane. In some species of (dogonium this has 
the f i he prima 
detected beneath the pore a secondary membrane, which in its t 
becomes perforate. In other species ot this genus an annular dehis- 
a 
mother cells. In such case the two supporting cells (seen in optical 
vertical section) are tetragonal, and sustain the oogonium only. Such 
oogonia the author denominates “ erect.” t for ‘the most part 
oogonia arise from oblique division of the incther or grandmother cell. 
Of the supporting cells in such case one or other (in diverse 
a double nature, some times “ erect,’ arising by horizontal division, 
Dr. Wittrock adds a few remarks ‘respecting the fixity of the 
specific characters in these plants, of which, indeed, with but a small 
fiactional proportion of his great experience, we ourselves feel very 
] assured. i 
which are ordinarily of minor importance, as, for instance, the dim 
sions of the cells, the position of the dwarf males on the female nla 
and such like. 
As illustrations ua this constancy the author adduces examples of 
CE. erispum (Hass.), Wittr., gathered from the a , which coincided 
Sw 
in even yo most minute details with hid Wiacitacas . 
examples of @. upsaliense, Wittr., Bulbochete fabio a, a 
and of many others taken in Greenland andi ope were inter se in no 
way different; B. elat tr., from 
Tasmania absolutely agreed in all their parts with Swedish examples. 
As regards the geographical distribution of the family, they 
