558 P. GEDDES ON THE PHENOMENA OF VARIEGATION AND 
some cases developed a nucleus, in others none) sometimes even half surrounds 
the innermost cellulose capsule of the adjacent green cell, and looks almost as 
if it were going to enclose it altogether. Such buds as these we have been 
imagining, arising as they would from the colourless ectoplasm of the green 
cell, would necessarily be themselves colourless. And instances are not wanting 
in vegetable and even in animal histology of the mdependent development of a 
nucleus and nucleolus within a cell. 
It is possible to verify this hypothesis of the origin of the white cells by 
direct observation. Generally the colourless cells seem totally distinct and 
separate from the coloured (figs. 1, 2, 4a, &c.), but occasionally one can see 
with the utmost clearness (figs. 4b, 19, 27) the process of formation of the 
colourless cells by the intrusion of the colourless ectoplasm of the green cell 
into an intercellular space. In fig. 20 are to be seen pseudopodium-like 
processes of colourless protoplasm pressing into soft swellings of the cellulose. 
At figures 19 and 27, the intercellular space is being filled up by a flow of such 
protoplasm from the green cell; while in fig. 44 the formation of a lateral bud 
is going on. 
In this Alga, then, we have simultaneously in progress two distinct modes of 
cell-formation ; first, the ordinary process of vegetative growth by transverse 
fission ; secondly, a process of gemmation tolerably similar to that which takes 
place in Torula. The cells produced by this second process are often to be 
seen dividing transversely (fig. 31), and it is not impossible that they may also 
give rise to new colourless cells by the same process as that by which they 
themselves were produced (figs. 19, 28). 
The Alga in question is also of some interest from the physiological point of 
view. It would be interesting to ascertain how plants so nearly destitute of 
chlorophyll as that represented in the last figure, which possesses only two cells 
capable of decomposing carbonic acid, can possibly live and grow. 
EXPLANATION OF THE PLATE. 
(Figures mostly drawn with Hartnack, Oc. 3, Obj. 7 or 9.) 
Fig. 1. Young growing fronds, showing (a) colourless buds of various sizes; (0) an originally 
colourless shoot of which the cells have almost all developed chlorophyll. 
. A frond bearing a terminal colourless shoot, and showing indistinctly the capsular 
arrangement of the cellulose. 
a 
03 
i) 
Fig. 3. Young frond treated with weak potash solution, showing very distinctly the capsular 
arrangement of the cellulose. 
Fig. 4. Frond showing (a) young colourless cell devoid of nucleus; (>) another budding off 
from green cell. 
Figs. 5, 6, 7, 8, 9, 10. Fronds showing outgrowths and thickenings of the cellulose alone. 
