SCIENTIFIC SUMMARY. 
449 
spaces between the joists and branding of a chamber-floor. He thinks, 
therefore, that by filling this space with a material which destroys the 
fungus, the prevention of dry-rot may be effected. The substance which 
he considers especially effective for the purpose is the tank-waste from 
alkali-works. This, he says, u may be had at all alkali- works for carting 
away.” 
Hawaiian Plants. — A critical list of the plants of the Hawaiian Islands 
is being brought out in the Proceedings of the American Academy by Mr. 
Horace Mann. This is not, however, the first. Indeed, it must only be 
regarded as a supplement to the fine work which was executed by Dr. 
Berthold Seemann, the editor of the Journal of Botany. 
No new Genera of Plants in the year 1900 ! — In a curious statistical paper 
read by M. de Candolle at the International Botanical Congress, the 
author expressed his belief that by the end of this century botanists will 
have become acquainted with every genus of plants on the face of the 
globe, and will thenceforth occupy themselves with only species and 
varieties. The facts on which M. de Candolle bases this opinion is, that 
the number of new genera has diminished in a certain arithmetical order, 
while the number of plant-seekers has proportionally increased. 
The Fall of the Leaf. — M. Trecul has recently presented to the French 
Academy a most valuable series of memoirs on the structure of the u proper 
vessels ” of the order Terebinthaceee. In concluding one of his recent 
memoirs, he calls attention to a phenomenon which occurs just before the 
fall of the leaf, and which is not unlike the process which accompanies the 
shedding of horns in animals. It consists in the obstruction of the 
li proper ” vessels at the base of the petiole (foot-stalk). This obstruction is 
effected by the multiplication of cells, which first shows itself in the parietes 
of the vessels. The cells increase and multiply until at last the vessels 
are completely choked up in the neighbourhood of the insertion of the 
leaf, although in other portions the vessels retain their normal characters. 
The Contractions of the Sensitive Plant. — These have formed the subject of 
two essays published in the Comptes Bendus for July and August, and 
written respectively by M. P. L. Bert and M. de Blondeau. The chief 
conclusion at which Mr. Bert arrives is, that the natural and regular move- 
ment of the leaves is produced by a different cause from that of sudden 
contraction resulting from contact with the fingers. Ether seems to have no 
effect upon the former, but it produces an anaesthetic effect which prevents 
the latter. M. Blondeau’s enquiries are more important. M. Blondeau 
experimented on the plants with the induced galvanic current of a B.uhm- 
korfi’s coil. He submitted three plants to the influence of the electric 
current. The first was operated on for five minutes ; the plant when left to 
itself seemed prostrated, but after a while (a quarter of an hour), the leaves 
opened, and it seemed to recover itself. The second was acted on for ten 
minutes. This specimen was prostrate for an hour, after which it slowly 
recovered. The third specimen was galvanised for twenty-five minutes, but 
it never recovered, and in twenty-four hours it had the appearance of a 
plant struck by lightning. A fourth plant was etherised, and then 
exposed to the current. Strange to say, the latter had not any effect, the 
leaves remained straight and open j thus proving, says M. Blondeau, that 
