360 MR. 8. LE M. MOORE’S STUDIES 
and the positively and negatively fragmented states of the chloro- 
phyll, it is clear that a large amount of condensation is the result 
of its exposure to abnormal light or darkness; this is especially 
well seen when contraction takes place without fragmentation, 
as occasionally in Selaginella (fig. 7 d), Mesocarpus (figs. 20 e, 
22 a), and in Chetophora (figs. 12 c, d, e). It appears then that, 
paradoxical though it may sound, fragmentation and condensation 
are really the same phenomenon, the only difference between 
them being that in the former condensation is more violent along 
certain lines than along others, thus entailing disruption, whereas 
in the latter it proceeds equally all round. It will be necessary 
to refer to this point yet once more (see p. 374). 
The long time taken by Selaginella Martensii over negative 
fragmentation is only what might be expected, seeing that negative 
effects are more slowly produced in shade-lovers than in plants 
with protoplasm toned to higher grades of illumination. It was 
shown in my previous memoir that aquatics are toned to low 
light: how comes it, then, that negative condensation and frag- 
mentation are brought about with comparative rapidity in such 
types as Draparnaldia and Chetophora? The answer is that 
these latter are adapted to strong light because of their liability 
to be carried up to the surface of the water by bubbles of disen- 
gaged oxygen; this is an incidentaladvantage to the alga, because 
a rapid rate of assimilation is thereby assured. It isa significant 
fact that the chromatophore of the fixed Batrachospermum monili- 
forme and Chantransia pygmea takes longer to fragment than 
does the chlorophyll of the above-mentioned free alge. 
But in order that the chlorophyll may condense or fragment, 
darkness is not essential. In low grades of illumination precisely 
the same effects follow as in the dark (Draparnaldia, Chetophora, 
Mesocarpus). There is therefore an interval in the photrum— 
which may be called the “ orthotactic " interval—within which 
alone the chlorophyll retains its normal form. I hope to treat 
of this matter on a subsequent occasion. 
Further Observations on Photolysis. 
In my previous memoir (Journ. Linn. Soc.(Bot.) xxiv. pp. 212, 
234) it was mentioned :— 
I. That the chlorophyll of sun-loving types is negatively 
apostrophized more rapidly than that of shade-lovers and aquatics. 
II. That the positively apostrophized chlorophyll of sun-lovers 
