1908] CURRENT LITERATURE 63 
position of the guard cells, the maximum diffusion capacity of the pore being 
seldom (if ever) utilized. A rhythmic variation in the transpiration rate was 
found to be independent of the stomatal rhythm. As to the latter, Luoyp finds 
that, aside from the indirect effect of high relative humidity in reducing the water 
loss and so favoring the opening of the stomata, there is no relation between the 
humidity and the position of the guard cells. He finds no closure of the stomata 
in anticipation of wilting, but during wilting a slow closure, without the prelimi- 
nary opening attributed to them by Francis DARWIN. 
Lioyp also attacked an interesting problem in the supposed photosynthetic 
activity of the guard cells. He finds evidence of amyloplastic but none of chloro- 
plastic activity, and concludes that the movements of the guard cells are related 
to their accumulation and dissolution of starch derived from the chlorenchyma, 
rather than to any photosynthetic products of the guard cells themselves. 
This is a careful and thorough piece of work, highly creditable to the labora- 
tory from which it comes. The experimental evidence is now at hand supporting 
conclusions which have been held by some physiologists for some years as highly 
Probable on purely physical grounds.—C. R. B. 
The timbers of commerce.—A second edition of BOULGER’S Wood, revised 
and enlarged, has appeared.* It deals with 1ooo kinds of wood, and includes 
Most of those known in general commerce. The first part (pp. 121) discusses 
wood in general, under such topics as origin, structure, development, classifi- 
cation, defects, selection, uses, supplies, and tests. The second part presents the 
woods of commerce, giving in each case the source, character, and use. The 48 
Plates are from photomicrographs of sections, and are intended to show the dis- 
tinctive microscopic features. Such a book is encyclopedic, and therefore for 
Its purpose it is extremely useful. The demand for a second edition speaks well 
for the favorable reception of the first—J. M. C. 
Knuth’s Handbook.—The second volume of Davis’ English translation of this 
encyclopedic work has just been issued by the Clarendon Press.? The original 
volumes and the first volume of the translation were reviewed in this journal,*° so 
that the general scope and character of the work have been noted. The pres- 
ent volume includes observations on flower pollination made in Europe and 
In the arctic Tegions, and is a great mass of observations upon species ranging 
through the natural orders, from “Ranunculaceae to Stylidieae.” Such a book 
“annot be reviewed, for it is an encyclopedia. It can only be announced, and 
PRC cee ET 
_ * Bourcer, G.S., Wood, a manual of the natural history and industrial applica- 
tions of the timbers of commerce. 8vo. pp. xi+ 348. pls. 48. London: pais 
Amold. 1908. $4.20. 
é ° Knuru, Paut, Handbook of flower pollination. Translated by J. R. Arvs- 
°rtH Davis. Volume II. 8vo. pp: viii+ 703. figs. 210. Oxford: Clarendon Press. 
Half morocco 35s.; cloth 31s. 6d. 
*° Bor, GAZETTE 28: 280. 1899; 28:432. 1899; 422494. 1906. 
