386 MR. 8. LE M. MOORE’S STUDIES 
to previously unoccupied walls, since in medium diffused light the 
grains are set upon walls bounding intercellular spaces, where- 
from they move in sunlight on to the intercellular septa—a cir- 
eumstance which would seem to imply, upon Schimper’s theory, 
a difference in behaviour towards carbonic acid and oxygen 
between mesophyll- and palisade-chlorophyll, which is very un- 
likely. Itis submitted that the mechanical reasons put forward 
in the previous memoir fully account for all the phenomena 
attendant upon systrophe. And when Schimper's idea is tested 
by the questions, How is it possible to predicate linear movement 
of a gas? and How can the removal of chlorophyll from one 
part of a cell to another protect it from the access of a gas readily 
diffusible through the wall? acquiescence therein seems quite 
out of the question. AltogetherI fear there is but slight chance 
of my coming io an agreement upon these matters with this 
deservedly celebrated botanist. 
EXPLANATION OF THE PLATES. 
[Except where otherwise stated, the drawings are not to scale.] 
Piare XIII. 
Figs. 1-10. Selaginella Martensii. 
Fig. 1. Cup-shaped cells of the upper epidermal layer with the chlorophyll in 
its diffused-light position, from a transverse section of a leaf. 
2. A horseshoe-shaped chloroplast from the base of a leaf in diffused 
light. This, and all the following, are surface views. 
3. Fragmented or dividing chloroplasts from basal cells. 
4. A basal cell; its chlorophyll has divided into four grains. 
5. A lower epidermal cell with a rosary-chain of chlorophyll grains. 
6. Chlorophyll bodies from the lower epidermis: d, grains dividing. 
7. Figures illustrating the effect of two and a half hours’ insolation: 4 
and b, chloroplast apostrophized; c, dumb-bell chloroplast, pro- 
duced by two portions being urged towards opposite walls of the 
cell; d, condensed mass, showing, however, at one point a tendency 
to fragmentation. 
8. Various stages and forms of positive fragmentation with colourless 
plasma-bridges and exposed nucleus (7); the colourless plasma is 
unshaded: d and e, after four and a half hours’ insolation; the rest 
after two and a half hours. 
9. A chlorophyll body moving into negative apostrophe, but still attached 
by fine colourless pseudo-plasmolytic threads to the limiting layer 
