260 Mr. J.S. Sanderson on the Embryogeny 
bryogeny. We shall sce as we proceed, that we are now enabled 
to construct a morphological type of development complete in all 
its parts, and applicable to all the hitherto investigated orders of 
phanerogamous plants. 
Mippuris vulgaris belongs to the natural order Halorageacee, 
which contains only three British genera, Myriophyllum, Hip- 
puris and Callitriche, all the species of which are water-plants 
with floating and submerged leaves. They appear to be distin- 
guished by their submerged leaves possessing distinct bundles 
of spiral vessels, a fact which may be well seen in the common 
Callitriche verna, and has been lately shown by Barnéoud in those 
curious plants the Trapas which float on the rivers of Southern 
Europe, and are considered by many botanists as belonging to 
this order. 
The ovary of Hippuris is one-celled, containing a single pen- 
dulous ovule, attached nearly at its apex by a fleshy funiculus. 
In its earliest condition I have not had an opportunity of ex- 
amining it. If however it be examined at a period considerably 
before that of impregnation and before the development of the 
solitary anther is completed, it is observed to have become com- 
pletely anatropous. The nucleus lies loosely in the cavity formed 
by the envelopes, which completely surround it, attached to the 
chalaza. The envelope is not distinguishable into primine and 
secundine, and extends considerably beyond the apex. It con- 
sists of small hexagonal cells arranged in series, each contaiming 
a nucleus. On one side, the raphe, consisting of a bundle 
of imperfect spirals, is seen passing from the hilum to the 
chalaza. 
The nucleus, the structure of which cannot be seen on account 
of the opacity of the envelopes without dissecting it out, consists 
of a large cell, the embryonic vesicle, extending from its apex to 
about two-thirds of its length, which is surrounded by a single 
layer of very transparent, gelatinous-looking nucleated cells, 
which are however deficient at the apex, at which point the em- 
bryo-sac seems to be totally uncovered. 
Contained in this embryo-sac is seen the embryo-vesicle. This 
body consists of a single elongated cell attached to the free ex- 
tremity of the embryo-sac. ‘This cell (the embryo-vesicle) con- 
tains a granular protoplasm in which here and there globules are 
observed to float. It probably originates at a very early period 
from the micropyle-end of the embryo-sac, but I have not been 
able to trace it at any earlier stage than that represented. The 
form which it presents, of an elongated cell attached to the end 
of the embryo-sac next the micropyle, and smaller at its attached 
than at its free extremity, is prevalent throughout the Scrophula- 
riacee, Crucifere, and other orders. 
