1903] CURRENT LITERATURE 77 
account is based on the study of material collected by Dr. F. C. Newcombe 
from Alliford Bay, Skidegate Inlet, Queen Charlotte islands, and is illustrated 
by a number of photographs and photomicrographs, which testify to the 
admirable preservation of the fossil. The author concludes that the fossil 
represents a plant of the general habit of Osmunda regalis, but is much 
larger than any of the species of that genus found in North America. _ Inter- 
nally it resembles Osmunda on the one hand and Todea on the other; but 
the resemblance seemed on the whole to be closer to Osmunda than Todea, 
so the fossil is included by the author in the genus Osmundites.— E. 
JEFFREY. 
HABERLANDT sums up the present data of the statolith theory of geo- 
tropic preception,® prefacing his paper with a short historical account of the 
development of the same theory for animals. He answers certain objections 
which have been raised and contributes some new support to the theory, which 
now seems reasonably established for a considerable number of plants. 
Starch-bearing cells of the root cap in roots and of the starch sheath in stems 
(which is present in the majority of phanerogams, although Fischer, investi- 
gating too old portions of the stem, found it often wanting) are the preceptive 
organs, except in certain cases, where the geotropism is limited to the 
nodes, or where sharply differentiated groups of cells with movable starch 
Srains replace the absent starch sheath. The preceptive apparatus is found 
to have degenerated in stems which have lost their geotropic sensitiveness, 
and to be lacking in organs which show no reaction to gravity. In general 
the root caps of apogeotropic climbing roots either contain no starch grains 
or non-motile ones. In orthotropous organs the protoplasmic membranes 
next the lower and upper transverse walls of the preceptive cells are not sen- 
sitive; only the membranes of the tangential longitudinal walls are irritable, 
and especially that of the outer wall in apogeotropic organs and that of the 
inner wall in positively geotropic organs. Whether both tangential walls of 
the same cell are sensitive is uncertain. In the nodes of grasses there is no 
ground for admitting this. The protoplasmic membranes on the radial walls 
are probably not sensitive. Any process which removes the starch from the 
Starch sheath at the same time stops geotropic response, which, however, 
may begin again when the starch is regenerated. Czapek’s demonstration of 
this in roots, from which starch disappeared when they were inclosed in plaster 
Casts, is now supplemented by Haberlandt’s experiments in removing starch by 
subjecting plants to low temperatures and then bringing the protoplasm into 
a condition of sensitiveness by raising the temperature. Until some sabia 
have elapsed and starch grains have begun to appear, the geotropic sensitive- 
ness does not manifest itself. Further experiments show that the action of 
gravity as a stimulus rests upon the static pressure of solid bodies. Further- 
3° HABERLANDT, G., Zar Statolithentheorie des Geotropismus. Jahrb. Wiss. Bot. 
38: 447-500. fig. 7. 1902 
