 Fecundation in Orchidee and Asclepiadea. 711 
as in Cypripedium, but in many cases in the parenchyma or 
internal cells of the tissue, especially when these are free from 
deposition of granular matter. 
In the compressed cells of the epidermis the nucleus is in 
a corresponding degree flattened ; but in the internal tissue it 
is often nearly spherical, more or less firmly adhering to one of 
the walls, and projecting into the cavity of the cell. In this 
state it may not unfrequently be found in the substance of the 
column, and in that of the perianthium. 
The nucleus is manifest also in the tissue of the stigma, 
where, in accordance with the compression of the utriculi, it 
has an intermediate form, being neither so much flattened as in 
the epidermis, nor so convex as it is in the internal tissue of the 
column. | 
I may here remark, that I am acquainted with one case of 
apparent exception to the nucleus being solitary in each utricu- 
lus or cell, namely in Bletia Tankervillie. . 
In the utriculi of the stigma of this plant I have generally, 
though not always, found a second areola apparently on the 
surface, and composed of much larger granules than the ordi- 
nary nucleus, which is formed of very minute granular matter, 
and seems to be deep seated. 
Mr. Bauer has represented the tissue of the stigma in this 
species of Bletia, both before and as he believes after impreg- 
nation; and in the latter state the utriculi are marked with 
from one to three areole of similar appearance. 
The nucleus may even be supposed to exist in the pollen 
of this family. In the early stages of its formation at least 
a minute areola is often visible in the simple grain, and in 
each of the constituent parts or cells of the compound grain. 
But these areolz may perhaps rather be considered as merely 
the points of production of the tubes. 
VOL. XVI. 4x This 
