IN VEGETABLE BIOLOGY. 361 
remains in apostrophe when removed to darkness, under which 
circumstances that of shade-loving plants comes out more or 
less into epistrophe. 
During June of last year (1887) the following types were found 
to have the chlorophyll of their lowest layer of mesophyll t cells in 
apostrophe within twenty-four hours in darkness; those to which 
an * is prefixed had massed grains within the above period. 
Cheiranthus Cheiri. Petroselinum sativum. 
Capsella Bursa-pastoris, Centaurea cyanus. 
*Platystemon californicus, Helianthus tuberosus. 
Linum grandiflorum. Campanula Medium. 
Pisum sativum. Limnanthes Douglasii. 
Lathyrus odoratus. *Solanum nigrum. 
Phaseolus vulgaris. S. tuberosum. 
Prunus domestica. Spinacia oleracea. 
In a few shade-lovers, on the other hand, negative apostrophe 
was much more slowly induced, thus :— 
Viola odorata. Apostrophe still imperfect after 10 days’ 
darkness (fig. 18). 
Circea lutetiana. Apostrophe still imperfect after 4 days’ 
darkness. 
Hedera Helix. Apostrophe stil imperfect after 3 days’ 
darkness. 
Vinca minor. Apostrophe still imperfect after 3 days’ darkness. 
Nemophila insignis. Apostrophe partial in 24 hours; not 
complete in some cells after 5 days. 
Mercurialis perennis. Apostrophe complete within a week or 
10 days. 
Polygonatum multiflorum. Apostrophe incomplete in 4 days. 
Much the same story was told by four aquicolous types :— 
Hypericum elodes. 
Drosera rotundifolia. Het incomplete in 4 days. 
Hydrocotyle vulgaris. 
Potamogeton crispus. Apostrophe at tip of leaf nearly perfect 
within 24 hours; but subsequent stages very slow, so that 
the movement had not been completed in eight days; 
further down the leaf progress is still lower. 
The Ranunculuses might at first sight seem to be exceptional, 
that is if R. sceleratus and R. bulbosus are to be taken as types 
t Here and elsewhere I have used this term to denote all the internal thin- 
nd parenchymatous elements of the leaf except palisade-tissue and bundle- 
eath. 
