IN VEGETABLE BIOLOGY. 857 
whether epistrophe would show itself, having, unfortunately, 
perished from drought during my absence from home *. 
We have seen that the chlorophyll body of Selaginella Mar- 
tensii may break up in sunlight and in darkness, and I shall now 
show that this is not a peculiarity of that type. The chlorophyll 
bodies of the larger cells of Draparnaldia glomerata, Ag., are 
arranged in a ring round the wall halfway up the cell. From the 
ring narrow, straight, or curved processes are given off which 
pass upwards and downwards, sometimes reaching to the cell’s 
bounding walls (figs. 11 a, b). Instead of being continuous, the 
ring may consist of a number of hollow spaces bounded by slender 
threads of chlorophyll; it then presents a reticulate aspect. The 
chlorophyll body is pale green; scattered through it are a few 
pyrenoids. Forty-eight hours’ sojourn in the dark may suffice to 
cause great changes, for in some of the cells the processes are 
now seen to be greatly shortened, in consequence of which the 
ring has become more or less torulose (figs. 11 c, d) f. After 
three days’ darkness + the chlorophyll body may form either 
a complete and frequently torulose ring lying across the cell 
at its centre or closely applied to a terminal wall, or it may 
have condensed into a spheroidal, subspheroidal, or irregular 
mass, or have undergone fragmentation into two or more 
masses of varying shape placed at any part of the cell, and 
either quite free from each other or connected by plasma-bridges 
(figs. 11 e-g), and these masses may themselves betray a tendency 
to division (fig. 11 A). After a short time even those rings 
which have, until now, retained their original position with respect 
to the cell’s long axis, lose it and come to lie in any plane, some- 
times reaching from corner to corner; at fig. 117 is shown one 
of these rings, in which fragmentation has just commenced. After 
* A few words concerning the photric method of the former memoir will not, 
it is hoped, be considered out of place here. The imperfections of that method 
have already been dwelt upon, the chief drawback to accuracy being contracted 
space, especially near the right and left ends, and variations in the illuminant 
value of the several points in consequence of variation in the intensity of sun- 
light. In order to construct a series of accurate intervals, it will be necessary 
to employ as a standard some constant source of light of known intensity—the 
electric lamp should answer all requirements—in a space extensive enough to 
contain all grades of illumination up to perfect darkness. 
t In these and the other figures only the proximal part of the ring is shown, 
å t These times apply to the summer; in autumn (October) the process is 
ower, 
