1915] ; CURRENT LITERATURE 79 
the useless nitrogen comethes with the oxygen not required may ssh Steninates 
and set free in the floats ‘‘in order to serve a mechanical purpose.” He sug- 
gests that since the proportion of oxygen in the vesicles is less than in atmos- 
pheric air or in air dissolved in sea water, the plant must use up some of the 
oxygen ‘“‘for other purposes than levitation.” This last suggestion evidently 
means that the gas is modified by the metabolism of the tissues through which 
it passes. 
In regard to (3) we shall await with interest to see whether the absence 
of carbon dioxide from the floats of marine algae is confirmed by other workers 
on other species. 
On the whole, the paper is a clear, clean-cut statement of the problem and 
of the results of the investigation, although in a few places its scientific value 
might be improved by assuming a less teleological point of view.—GEORGE 
Rice. 
Cecidiology. y 
STEWART? on the gall caused by Andricus punctatus Bassett. The author has 
made a very careful study of the histology of the gall, which he has compared 
with the histology of tissues formed in the healing of wounds. In his sum- 
marization on this point he says: 
he following conditions in this gall can be comtelated with similar conditions in 
traumatic tissue: (1) a recapitulation of similar conditions of ray structure; (2) a 
vertical shortening of the broad rays; (3) the presence of ball-formations in the wood, 
which appear only in tangential sections; (4) a parting of the fibers in the vicinity of 
the larval chambers, similar to the condition resulting from longitudinal wounds; 
(5) isodiametric parenchyma cells around the base of the larval chambers with irregu- 
larly distributed fibers and other woody elements among them; (6) a great reduction 
in the number, or an entire lack of vessels; (7) a shortening of many of the cells of the 
wood; (8) absence of distinct annual rings of growth; (9) a suggestion of the return 
of the cambium to normal activity after a time; (10) woody inclusions in the bark. 
Unfortunately, the bibliography is not satisfactory in that it includes some 
papers which have much less bearing on the subject than certain papers which 
are not included. Also, some of the statements in the first part of the paper. 
concerning our knowledge of the anatomy of galls are misleading. The 
reviewer also questions the statement of the title of the paper, in that the 
inclusion of the generic name of the gall insect would have made the title much 
more suggestive to those who may wish to become informed on the literature 
of the subject. However, the author has brought out a number of points 
which are frequently overlooked by students of abnormal plant growths. 
Another very excellent paper is by Lutman™ on club root, in which the au- 
thor discusses the relation of Plasmodiophora Brassicae to its hosts and the 
i 
9 STEWART, gorse “ea on the anatomy of the punctatus gall. Amer. Jour. 
Bot. 1:531-546. pls. 
 Lutman, B. a3 rae on club root. Univ. Vermont, Bull. 175. pp. 27. 1913- 
