270 - ‘THE JOURNAL OF BOTANY 
THE BRITISH ASSOCIATION. 
A LARGE and echo shri of before met at Cam- 
bridge during the British Association week. Among the number were 
some well-known foreign botanist raiblddivye Professors Engler, 
Klebs, Reinke, Czapek, Chodat and Bertrand, Drs. Eriksson, Lotsy 
and Peirce, and the Sapa botanists Fujii and Miyake. The 
President, Mr. Francis Darwin, took as the subject of his address, 
“The Perception of the Force of Grav ity by Plants.” The address 
was an exposition and defence of the statolithic theory, which claims 
that the origin of the stimulus, in response to which geotropic curva- 
tures take place, lies in the impact of the starch-grains on the ¢ ell- 
walls as a result of the alteration in forthe of the organ. Assuming, 
as follows from Andrew Knight’s original experiment, that weight of 
some kind supplies the stimulus, we may seek its origin with Pfeffer 
and Czapek in the hydrostatic pressure of the cell- contents on the 
wall, or with Noll inthe impact of imperceptible pa aie or with 
Haberlandt and Nemec in the falling starch-grains or statoliths. 
r. Darwin considered the hydrostatic pressure theory inadequate, 
and that of Noil impracticable, while the statolithic theory not only 
affords a practicable solution of the pera but is supported by 
a considerable weight of experimental evidence. There is a striking 
parallel between the distribution of the falling SS aie ae on the 
-one hand, and those organs and tissues, on the other, in which 
poin 
onion—that is to say, in those parts which are recognized as essen- 
tially gravisensitive cells—but not elsewhere in the plant. The ex- 
mental evidence, if not absolutely convincing, has not revealed 
any absolute bar to a belief in the statolith theory, and has brought 
to light a number of facts which harmonize with it in a remarkable 
anner. 
Among the Bat a Mea. and EAS were several involving 
questions So é eneral interest. ‘The existence of a nucleus in the 
Cyanophycea as sieieiksel by Sis feasors Chodat and Zacharias, on 
the one hand, and Mr. Wager, on the other. The two former deny 
that the central matter bears any relation to the nucleus as we 
understand it in the higher plants; the latter insists on the presence 
of a sort of primitive simple nucleus. Prof. Hriksson gave an ac- 
count of ea og bg mp! theory of the origin of rust in corn and 
other Shoes ; he traces the disease to the presence of protoplasmic 
seed, ide carrying on the disease to the next generation; this 
taining that the disease is always the result of infection by a 
from iat the spore germinates, the germ-hypha enters thr ough 
en, if the host-plant is a favourable one, proceeds to 
infect the surrounding tissue. The general opinion seemed to be 
