936 The American Naturalist. [October, 
evident, but the explanation of the intensified zones and of the second 
inhibitory zone, sometimes seen, is not very apparent. It is probable, 
however, that the dissolved oxides or salts of the metals are in too 
great concentration in the clear zone, and that the trace present in the 
intensified zone may stimulate growth. This does not explain the sec- 
ond inhibited zone. The length of time it is necessary to leave the 
metals in contact with the agar, in order to develop the inhibitory 
action was tried with brass, copper, cadmium and zinc. Plates of 
Staphylococcus p. a, were made in the usual way and the metals put on 
and removed at various intervals. With cadmium there was a clear 
space where the metal had lain and for 1 mm. around, where the metal 
had been left on for a minute. Where the metal had been left on for 
3 or 4 minutes or more the clear space usually extended over 3 mm, 
around where the metal had lain. With zinc the results are similar as 
regards length of time, but the edges of the clear zone are not well de- 
fined and there is an intensified zone that is not apparent with cad- 
mium. With brass there was no effect produced by leaving the metal 
on for 36 minutes; after this there was more and more marked inhibi- 
tion up to 50 minutes, but no clear space except where the metal was 
on for a longer time than this. With copper no visible effect was pro- 
duced in less than 36 minutes. After this time there was more and 
more marked inhibition, but only where the metal had been allowed 
to lie on for 50 minutes was there a clear space. The whole paper is 
very suggestive and is commended to experiment station workers and 
all who have to deal with problems relating to fungicides and germi- 
cides. Probably the increased development and prolonged activity of 
chlorophyll in foliage sprayed with Bordeaux mixture is also attribu- 
table to the stimulating effect of the minute traces of copper that must 
pass into the leaves. The paper contains 10 pages and 11 figures, and 
has been distributed as a reprint—Erwin F. SMITH. 
ZOOLOGY. 
Antivenine.—Prof. Fraser has laid before the Royal Society of 
Edinburg some important results of his admirable experiments on 
snake poisons and their antidote. His method is to ascertain the min- 
imum lethal dose for an animal, to begin experimenting upon a similar 
animal with a smaller dose. After a short interval he increases this 
