IN VEGETABLE BIOLOGY. . 229 
of which, instead of speedily massing in darkness, remain in 
simple apostrophe. In this case it might be argued either that 
the effects of light must soak out with unusual rapidity (in which 
event we should expect that rearrangement of the grains con- 
sequent on long confinement in the dark, to which the name of 
“negative epistrophe” or “astrophe” has been given, would set in 
much sooner than is the case), or else that the tone of the proto- 
plasm with respect to light must be rapidly lowered (which would 
result in ultimate massing—a very rare occurrence indeed in 
Funaria). The difficulty will, perhaps, vanish when it is remem- 
bered that the thickness of the Funaria-cell is much less than its 
length, so that the grains, very large relatively to the size of the 
cell, are more closely packed in apostrophe than in epistrophe; 
by this means the conditions favouring stasis are reinforced by 
impact of the grains against their neighbours, and the consequent 
loss of momentum and increase of friction. This, it is easy to 
conceive, may well be equivalent to the difference between the 
above conditions and the protoplasmie momentum ; and if equi- 
valence be once established, massing cannot set in. 
The theory here advanced may be shortly stated thus:— 
(1) Protoplasm is positively phototactic to light of medium 
intensity, and negatively so to high grades of illumination and to 
darkness. 
(2) The attracting and repelling actions of light impose a 
strain upon protoplasm, the time of recovery from which varies 
directly as the amount of the strain, t. e. as the sensitiveness of 
the protoplasm to light, and directly also as the period of ex- 
posure. 
(3) Lowering of the tone of protoplasm as respects light 
results from withholding that agent; at the same time photolytic 
effects remain stored up for a time in protoplasm after light has 
been shut out. It is upon the relation between lowering of the 
tone and soaking out of the effects of light that negative apo- 
strophe depends. | 
The view here advocated does not exclude the new doctrine, 
that it is mainly by the movements of protoplasm that the trans- 
ference of plastic materials from one part of a plant to another 
is effected. The doctrine may be said to be new because of the 
great extension of which it is capable from the discovery of pro- 
toplasmie continuity. It is well, however, to remember that 
LINN. JOURN.— BOTANY, VOL. XXIV, U 
