156 BOTANICAL GAZETTE [FEBRUARY 
gives descriptions, with bibliography and in some cases figures, of 15 species. 
PANTANELLI® gives a lengthy description of a mite (Eriophyes) of the olive 
and also a description of its gall. RUBSAAMEN,” continuing his studies on the 
European cecidia, describes, and in many cases figures, 42 species, 4 of w 
arenew. BAYER* ina paper on the cecidia of Bohemia gives a bibliography of 
32 titles and lists 198 cecidia. 
For a number of years the anatomy or rather the histology of cecidia has 
proved an interesting field for the European workers, but only in recent years 
has it attracted the attention of the American students. A recent paper is 
that of GREVILLIUS* on the anatomy of the thysanopterous cecidia of Vicia 
Cracca. This gall is very conspicuous because of the curling and twisting 
of the leaves which are infested with the insects, whose eggs can be found 
between the epidermis and mesophyll. In the more advanced stages the 
palisade cells lose their characteristic forms and become isodiametric. These 
galls never develop the complicated structures found in those produced by 
the hymenopterous insects. 
Although the physiological problems connected with the study of insect 
galls have long been looked upon with interest, the difficulties have been so 
great that few have had the courage to attack them. One of the recent papers 
on this subject is by NALEPA,3? who has taken up a study of the gall-inhabiting 
ants. This subject has been investigated by others, among them PEYRITSCH, 
who considered. light the most important factor because there were more galls 
on plants growing under shade than in the light. Natepa’s work took into 
consideration the relative importance of light, temperature, and moisture, 
and involved a number of experiments in which the insects were kept in cylin- 
ders, in which these factors could be controlled. In this connection he studied 
also other insects, such as Eriophyes, which he found were uninfluenced by the 
light. His results in general confirm the views of PeyrirscH.—MEL T. Cook. 
Transpiration.—RENNER® has published a paper on the physics of tran- 
spiration. It ad a number of important facts to the epoch- -making work of 
Brown and Escomse on multiperforate septa. He works out mathematical 
formulae for the resistance to the passage of water vapor offered by stomatal 
apparatus of various xerophytes. The experimental part is carried out with 
models having the shape of xerophytic transpiratory canals and with plants 
8 PANTANELLI, E., Un Eriofide nuovo sull’ olivo. Op. cit. 142-146. 
se oe ie Ev. H., Beitrige zur Kenntnis aussereuropiischer Zoocecidien. 
1c. 923-36. 
30 sey ee Les Zoocécidies de la Bohéme. Op. cit. 63-104. 
a aye he A. Y., Ein Thysanopterocecidium auf Vicia Cracca L. Op- cil. 
8:37-45. 19 
2 NA LEPA, A., Der Heliotropismus der Gallmilben und seine biologische Bedeu- 
tung. Op. c¢ 78-84. 
33 arab O., Beitrige zur Physik der Transpiration. Flora 100:451-547: 1910. 
