202 MR..S. LE M. MOORE'S STUDIES 
is more rapid in a cell when injury has been inflicted on it. Next 
on the list comes Frank *, who in 1872 made the movements of 
chlorophyll the subject of a careful study. He called by the 
name of * Epistrophe” the distribution of the grains upon the 
free walls and the parts of the wall bordering on intercellular 
spaces, and by that of “ Apostrophe " the arrangement upon the 
side-walls ; he also confirmed the statements of his predecessors 
that Epistrophe is more quickly assumed from dark-caused 
Apostrophe than vice versá. In addition to this Frank found 
Apostrophe to be brought about more slowly in large than in 
small cells, and the position of the chlorophyll grains to be largely 
dependent on the age and general condition of the cell. Shortly 
afterwards, the remarkable difference with respect to position in 
high and low light shown by the chlorophyll of Selaginella Mar- 
tensii was announced by Prillieux f ; and De Bary f, in the course 
of some observations made in conjunction with Strasburger on 
the life-history of Acetabularia mediterranea, noted a running 
together into small clumps of the grains of healthy tubes exposed 
for a few minutes to direct sunlight. In 1880 the subject was 
investigated by Stahl $, who begins his memoir with an interesting 
account of the effects of light upon the chlorophyll plate of a 
species of Mesocarpus, showing that the plate, set broadside on 
in diffused light, turns through an are of 90? on to its edge if 
the illumination be strong. Stahl objects to Borodin’s terms 
“Tagesstellung " and * Nachtstellung," remarking very appo- 
sitely that the chlorophyll of many plants remains in Tagesstellung 
throughout the night, and that in order to move it into Nacht- 
stellung exposure to sunlight is the only requisite. Frank’s 
terminology likewise fails to commend itself, inasmuch as by 
* Epistrophe " Frank understands the arrangement of the grains 
upon the superficial walls, and on those parts of the walls 
bounding intercellular spaces, whereas in diffused light chloro- 
phyll is disposed on the walls at right angles to the direction of 
incident illumination irrespective of their relation to intercellular 
* Pringsheim's Jahrb. f. wiss. Bot. Band viii. See also Bot. Zeitung, 1871. 
Prillieux had in 1870 (Comptes Rendus, tome lxx. p. 46) written a short account 
of the alterations in position undergone by the chlorophyll of Funaria hygrome- 
trica, which, however, had previously been recorded by Borodin. 
t Comptes Rendus, tome lxxviii. 1 Bot. Zeitung, 1877. 
$ Bot. Zeitung, 1880. Movement of the chlorophyll plate was first discovered 
by Wittrock (K. Svenska Vet.-Akad. Handlingar, Band v. 1878), who did not, 
however, suspect the agency of light. 
