PHYTOGENESIS. 233 
many of the cells in the epidermis of the Orchidee, an opaque 
spot, named by him areola, or nucleus of the cell. He subse- 
quently pursued this phenomenon in the earlier stages of the 
pollen-cells, in the young ovulum, in the tissue of the stigma, 
not only in the Orchidee, but also in many other Monocotyle- 
dons, and even in some Dicotyledons. 
As the constant presence of this areola in the cells of very 
young embryos and in the newly-formed albumen could not 
fail to strike me in my extensive investigations into the deve- 
lopment of the embryo, it was very natural that the consider- 
ation of the various modes of its occurrence should lead to the 
thought, that this nucleus of the cell must hold some close 
relation to the development of the cell itself. I consequently 
directed my attention particularly to this point, and was for- 
tunate enough to see my endeavours crowned with success. 
Before, however, I proceed to the communication of these 
observations, I must first give a somewhat more detailed 
description of the nucleus. As I have to treat of a peculiar 
and, I think, universal elementary organ of vegetables, I do 
not consider it necessary to apologise for applying a definite 
name to this body, and therefore call it Cytoblast (kuroe, 
(Aacroc) in reference to its function, which will be described 
hereafter. . 
This formation varies in its outline from oval to circular, 
according as the solid which it forms passes from the lenticular 
into the perfectly spheroidal figure. I have found the oval 
and flat cytoblasts more frequently in Monocotyledons, m the 
albumen and pollen; the globular chiefly in the Dicotyledons, 
and in the leaf, stem, articulated hairs, and similar structures ; 
no exclusive rule, however, can be laid down on this point. 
The colour of the cytoblast is in general yellowish, but it 
sometimes passes into an almost silvery white. I remarked it 
as being most transparent in the albumen of some water 
plants, in the unripe pollen, in some Orchidee, and also in the 
rudiments of the leaf of Crassula portulaca. Its excessive 
transparency renders it scarcely perceptible in the spores of 
some Helvelloids. It is coloured by iodine, according to its 
various modifications, from a pale yellow to the darkest brown. 
It varies considerably in size. It is in general largest in 
Monocotyledons, and in the albumen; and smallest in Dico- 
