of Hippuris vulgaris. 263 
series of researches, as far as they go, among the many to which 
this controversy has given origin. The facts which are brought 
forward by this author are confirmatory in the most important 
particulars of what had previously been ascertained by Hof- 
meister, Unger, and others, but are distinguished by the author’s 
inquiries having been carried to an earlier period in the develop- 
ment than had been arrived at by any previous observer in the 
families to which they refer, namely the Scrophulartacee and the 
Crucifere. 
In the Scrophulariacee generally, as in Hippuris, the embryo- 
vesicle assumes at an early period an elongated form, and its 
subsequent development is identical. Tulasne has traced it to 
its earliest origin in several species. He has shown that it is 
developed originally on the inner surface of the wall of the em- 
bryonal sac near its summit, but at a pomt quite separate from 
that at which the pollen-tube is applied. This vesicle, at first 
exceedingly minute, grows upwards in the cavity of the embryo- 
sac, until it assumes a form similar to that seen in Hippuris. 
These facts are important, as serving to point out more distinctly 
the strict correspondence between the morphological modifications 
of the same development as observed in the Scrophulariacee and 
other orders, with those possessed of distinct embryo-sacs, as the 
Orchidaceae. 
The researches before us also derive an additional interest 
from their showing the total inaccuracy of the observations of 
Prof. Wydler of Berne, (which were made on the same natural 
order,) who in the year 1838 set himself to support the theory 
of Schleiden, and from whose alleged facts that physiologist de- 
rived some of the most powerful supports of his views. 
In the Crucifere M. Tulasne has also accomplished all that 
can be done to perfect our knowledge of the embryogeny of the 
order. In particular he has described and figured distinctly the 
embryonal sac, the existence of which was doubted in that order, 
and has traced the embryonal vesicle from its earliest condition, 
that of a minute cellule attached to the micropyle extremity 
of the embryo-sac, up to that of a cylindriform cell filled with a 
granular protoplasm, at the period at which it should seem that 
fertilization takes place. 
Numerous other points of great importance might be men- 
tioned as illustrated by this admirable series of researches. They 
will well reward the perusal of all who take any interest in vege- 
table anatomy and physiology, and they are illustrated by draw- 
ings, which exceed in beauty and detail all their predecessors, 
although many of these have been beyond all praise. 
From the accurate knowledge of the facts connected with the 
. origin and development of the vegetable embryo, into the pos- 
