536 BOTANICAL GAZETTE [JUNE 
in many cases they are changed by their own activity and are not destroyed 
by hot alcohol. The enzyme nature of hydrogenase, however, is not. to be 
doubted. It performs its function by liberating nascent hydrogen which unites 
with the oxygen carried by the oxidase to form water or hydroxyl groups; the 
latter can be employed for the formation of metabolic products. By these 
formations the oxidation of other substances is prevented. “Reductase” is 
a contradictio in adjecto. ‘‘Catalase”’ is merely a term to designate the decom- 
position of H,O., and its place in the category of enzymes is extremely hypo- 
thetical. Amylocoagulase is the anti-enzyme of diastase in the sense that its 
action is just the opposite of that of diastase. The coagulase may be entirely 
obscured by the action of diastase, but it cannot be reversed. Cytocoagulase 
is another synthetic enzyme which acts in opposition to cytase. 
The chief value of the book lies in the mass of experimental details and the 
ingenious methods devised for the study of enzymes. It will find its greatest 
usefulness among those especially interested in enzymes, as the treatment is 
rather technical—Cuas. O. APPLEMAN 
Field manual of trees 
An addition to the already numerous tree manuals has come in the form 
of a thin pocket volume, 4.5 by 7 inches, bound in flexible leather, making 
it particularly convenient for field use. It is designed to include all the native 
and many of the introduced species north of Virginia and Kentucky and east 
of the prairie region. The features which recommend this manual are the 
numerous keys, all of which appear to be accurate and rather simple. 
include separate ones for the genera based on (1) summer condition, (2) winter 
condition, (3) flowers, and (4) fruit, as well as keys for species under each 
genus and a general classification of the wood of the trees. The descriptions 
of the species seem to be good, but it is certainly unfortunate that such well 
known trees as the black and choke cherry should appear under such scientific 
names as Prunus virginiana and P. nana respectively, and that the flowering 
dogwood should be removed from the genus Cornus. Whatever may be the 
arguments of the gage for such a course, it is certainly likely to lead to 
confusion, especially in a manual where no synonyms are given. One also 
misses the ahusitiiedle which have been a prominent feature of many recent 
volumes on trees.—GEo. D. FULLER. 
MINOR NOTICES 
Botanical researches of the Carnegie Institution—The annual report® 
for the past year gives an idea of the various lines of research completed and 
5 SCHAFFNER, JoHN H., Field manual of trees, including southern Canada and 
the northern United States to the southern boundary of Virginia, Kentucky, and Mis- 
souri, westward to the limits of the prairie. Columbus (Ohio): R. G. Adams & Co. 
1914. 16mo. pp. 154. Cloth $1.25. Limp leather $1.75. 
6 MacpoucaL, D. T., Annual report of the director of the department of botanical 
research. Carnegie Institution of Washington, Year Book No. 12 for 1913:57-87. 1914. 
