150 BOTANICAL GAZETTE [FEBRUARY 
Leaf structure.—Most botanists are familiar with the contributions of Dr. 
CocKAYNE to our knowledge of the flora of New Zealand and the adjacent 
islands. On his trip to the southern islands several years ago, he brought back a 
number of living plants which are now growing in the rockery of Canterbury 
College. These plants have been made the subject of an anatomical investigation 
by Miss Herrtotr.3* In spite of the uniform climate of the southern islands, 
many if not most of the plants reveal xerophytic structures. The author cites 
two conditions in these island regions which may be regarded as xerophytic. 
One is the frequence and violence of the wind, and the other is the peaty soil.— 
H. C. Cowtes. 
Forestry.—Two recent bulletins of the Bureau of Forestry will be of some 
interest to ecological workers. One of the bulletins3? describes the valley and 
ridge forests of Kansas and Nebraska and their economic possibilities. The 
natural extension of both types of forest is discussed, but this subject will be well 
known to all through work of Professor C. E. Bessey. The other bulletin’? is 
almost wholly of economic interest, but ecologists will find some notes on the 
natural reproduction of the white pine in the old fields of New England.—H. C. 
CowLes. 
Hygroscopic mechanisms.—STEINBRINCK, who has given particular attention 
to hydrophysics, summarizes for non- ces: readers the mechanisms of shrink- 
age and cohesion in plants.34 It is these which are concerned chiefly 
in the rupture of capsules and sporangia. The current conceptions as to the 
rupture of the latter particularly need correction, and the article is commended 
to students. In his Literaturiibersicht he has indeed overlooked American litera- 
ture on this subject—C. R. B 
Biology of Dunaliella—In 1905 Troporesco described35 Dunaliella as a 
new genus of Volvocaceae, giving an account of its structure and life history. In 
a second paper3® he has begun an account of certain “biological observations.” 
In this first instalment these observations deal with changes in the form of the 
body, cell structure, cell division, sexual reproduction, and the resting condi- 
tion.—J. M. C. 
31 HerRioTT, E. M., On the leaf structure of some plants from the southern 
islands of New Zealand. Trans. N. Z. Inst. 38:377-422. 1906 
32 KeLioce, R. S., Forest belts of western Kansas and Nebraska. U. S. Dept. 
Agric., Forest Service, Bull. 66. 190 
33 SPRING, S. N., The natural replacement of white pine on old fields in New 
England. U.S. Dept. Agric., Bureau of Forestry, Bull. 63. 1905. 
34 STEINBRINCK, C., Ueber Schrumfungs- und Kohisions-mechanismen von Pflan- 
zen. Biol. Centralbl. 26: 657-677, 721-744. figs. 28. 1905. 
35 Beih. Bot. Centralb. 18: 215-232. 1905. 
3° TEO , Observations morphologiques et biologiques sur le genre 
Dunaliella. pee a Sistiaicae 18: 353-371. pls. 2. 1906. 
