1922] CURRENT LITERATURE 499 
at some satisfactory method for quantitative estimation of vegetational values 
is of particular interest. The methods of the earlier workers were heterogen- 
ous and often confused. Later methods gained in the matter of clarity of 
ideas, but were highly complicated and exceedingly laborious. Present day 
effort is toward simplification, and in this the work of RAUNKIAER and BRAUN- 
BLANQUET is perhaps most promising. The latter’s paper, in addition to the 
effort toward clarification and simplicity, just mentioned, is notable for its 
proposal to classify his plants also according to their dynamic value, that is, 
in American terminology their successional value. He proposes a series of 
five valuations to be applied to the species in any given association, together 
with symbols for their convenient designation. His class names, with approxi- 
mate English equivalents, are aufbauend (constructive), erhaltend (maintain- 
ing), festigend (consolidating), neutral (neutral), abbauend, zerstérend 
(disruptive). The idea of progressive and regressive succession is thus clearly 
tulated. : 
The ecological implications in Firtr1ne’s contribution are all the more 
valid in that they are not directly intended. The author is a physiologist, 
and his primary concern is the avoidance of the artificial and abnormal condi- 
tions imposed on his material by the greenhouse methods of ordinary laboratory 
practice. He contends that the physiology of plants should be studied where 
the plants naturally occur, and insists on the study of climatic, edaphic, and 
biotic factors as they affect the space actually occupied by the plant in the 
field. This, of course, coincides with the activities of the younger American 
ecologists who are carrying physiology out of doors. 
PALMGREN’S study is one of migration, and thus implies the successional 
viewpoint throughout; it is the more noteworthy in that it was conducted on 
the Aland archipelago, almost within sight of Uppsala. These islands, he 
estimates, have not been emerged for more than 3500 years; moreover, they 
are high-boreal in position, so that an ecologist with the successional viewpoint 
can extract much aid and comfort from his conclusions. 
All this is gratifying to Americans, but as yet there is not much indication 
Fu 
Probably most American ecologists feel that still further simplification is 
need RAUNKIAER himself admits that his methods involve a good deal 
of iabor. Then there is also the element of time; it generally takes about 
two graduate ‘“‘generations” to establish a new idea.—FRANK THONE. 
Stomatal regulation.—Using Lioyn’s methods of studying stomata, which 
he thinks have been criticized without sufficient reason, Lorrrretp® has made 
6LorrFieLpD, J. V. G., The behavior of stomata. Carnegie Publ. no. 314. 
Pp. 104. 1921. 
