226 MR. 8. LE M. MOORE’S STUDIES 
says that (positive) apostrophe is favoured by sectioning, by 
exposure to abnormal temperatures, by diminution beyond a 
certain limit of a plant’s watery contents, and by withdrawal of 
oxygen from it, and by old age. Supporters either of Bohm’s or 
of Stahl’s theory are, upon each of these points, confronted with a 
difficulty precisely similar to that pointed out under the last head. 
Moreover Frank's list is not quite exhaustive, for poisoning is a 
ready means of inducing apostrophe. Why the grains of a plant 
treated with a 3-per-cent. solution of ferrous sulphate or ferric 
chloride should apostrophize at lower grades of illumination than 
another's not so acted on, is perfectly mysterious except upon 
the view that use of the poison has brought lowering of proto- 
plasmic tone in its train; in none of Frank's cases is the mystery 
less, nor less completely solved by the same method of reasoning. 
Frank, indeed, goes to the length of describing apostrophe as a 
“symptom of diminished vital energy ;” and although later dis- 
coveries have shown that this is too wide an assertion, yet there 
seems to be no doubt that to abnormal apostrophe, whether posi- 
tive or negative, this description well applies. 
Fourthly. If the protoplasm of aerophytes be more highly: 
toned, as respects light, than that of aquatics, it ought to betray 
more rigidity in the former; thus the positive effects of light 
should be less and take longer to bring about in the aerophyte 
than in the aquatic. That the disturbance caused by light is 
greater in the aquatic plant has been amply shown; its more 
rapid introduction is established by the table on p. 234, from 
which it may be gathered that even in low light the grains of 
Elodea require little longer to apostrophize than do those of 
aerophytes in direct sunlight (in good light a few minutes are 
sufficient for the purpose); and in bright diffused light Lemna 
trisulca chlorophyll is apostrophized in about a quarter of the 
time necessary for that of insolated aerophytes. Again, it is 
seen from the table that the almost entirely negatively apostro- 
phized grains of JL. trisulca are epistrophized in thirty-five 
minutes, whereas a corresponding movement in aerophytes is not 
completed until several hours have elapsed. Further comparison 
on this head is scarcely practicable, because of the long time re- 
quired to negatively apostrophize the grains of aquatics, and the 
consequent inroads upon the health of their protoplasm. How- 
ever, with this caution it may be pointed out that the partially 
apostrophized grains of Utricularia vulgaris were epistrophized 
