556 P. GEDDES ON THE PHENOMENA OF VARIEGATION AND 
direct sunlight there seemed to be as many colourless cells as ever, though it 
is well known that a few hours in such conditions suffice to develop chlorophyll 
in blanched vegetable cells. Nor did those kept in darkness show any distinct 
increase in the proportion of white cells to green. In fact, when the three 
pieces of flint were again placed together in the same aquarium, an attempt 
to identify them again by examination of the Algze they bore, failed com- 
pletely. 
I do not deny, however, the importance of the action of light, for I have 
found white buds more abundantly in winter than in summer ; but it is evident 
that such an experiment as the foregoing, twice repeated, excludes the hypo- — 
thesis of etiolation. Moreover, the long period over which my observations 
have extended, the many changes of climate and of circumstances to which the 
plants have been exposed, and above all, the fact that the white shoots were 
more abundant the more active and more vigorous the growth, are all 
arguments in favour of the normality of this mode of vegetation. I should, 
however, consider it premature to assign any specific or generic name before 
examining more specimens from other sources; and it may not improbably 
turn out that these phenomena of variegation may occur as a kind of sport in 
many species of Algee. 
The colourless buds, then, demand a closer examination. At one side of 
the frond or filament, and generally midway between two green cells, is often 
to be seen a slight prominence of cellulose enclosing a tiny droplet of colourless 
non-nucleated hyaline protoplasm (figs. la, 11). A farther stage is represented 
in fig. 12, where there are two similar but larger masses, and a farther still 
in fig. 13, where there are three; in sbort, all stages are to be found up to 
a comparatively long row of colourless nucleated cells, such as that represented 
in fig. 14 or 23. The existence of a series of perfect gradations between a 
single minute non-nucleated droplet of clear protoplasm, and a distinct row of 
nucleated and granular cells, shows that the colourless shoot arises in a way 
totally distinct from that by which the ordinary green cells are developed. 
Such transparent cells multiply by transverse division, and have also the 
power of developing chlorophyll. While the majority of the colourless shoots 
are sharply marked off by their colour and general appearance from the green 
part of the frond (figs. 13, 14), others are to be found in which there is a gentle 
eradation from white cells to green (figs. 1b, 15, 24, 28), the development of 
chlorophyll beginning at the base of the shoot, and proceeding upwards. 
Cases in which the colourless cells are irregularly interpolated among the 
green, as has been already said, are not uncommon. Sometimes one finds the 
cells of a green filament separated by the development of one or several colour- 
less cells (figs. 16, 19, 26); sometimes these may multiply greatly, so as to push 
the original green portions of the frond far apart from each other, and so 
