1912] CURRENT LITERATURE : 451 
tance in conserving moisture and regulating the flow of streams in a region where 
the water supply is of the utmost economic importance. This conservation is 
a Saar by the root system penetrating the soil and assisting percolation, 
Ww. at the same time the trees prevent erosion by shading the ground, by 
‘raking the force of hot winds, and by lessening evaporation. The most active 
destructive agent is fire, which rapidly sweeps the half-dry vegetation from 
the arid ood ar. in 
pes. Ts 
port of his belief that the protection of the chaparral cover is of great impor- 
tance in preventing the loss of water needed for irrigation. 
From the ecological viewpoint, the ‘“‘true chaparral,” which seems to be a 
climatic formation holding complete possession of its domain and — 
principally in California, is distinguished from “mock chaparral,’ which- is 
pioneer association of similar dwarfed trees occurring in the forest soe 
a 
The dominant members are various species of Adenostoma, Arctostaphylos, 
Ceanothus, and Quercus, while forms of Rhus, Cercocarpus, Rhamnus, and Ribes 
are among those of secondary Ree 
The study includes a consideration of the ecological relations and relative 
economic importance of the more abundant species, of the methods of control- 
ling fires, of restocking after fires, and of the possibility of introducing larger 
tree species. A map shows the distribution of this interesting forest formation 
in Californid—Gro. D. FULLER 
Stems of Diplolabis and Metaclepsydropsis—Gorpon”™ has described 
the hitherto unknown stems of Diplolabis Rémeri and Metaclepsydropsis 
ele 
tracheids, while in eopher e there is much parenchyma scattered 
among the small siarolt xylem elements. The leaf trace departs in each case 
as an elliptical strand with two lateral mesarch protoxylems. In the lower 
portion of its course, it may resemble in turn the petiolar bundles of Clepsy- 
hee Dineuron, or Zygopteris; but after its entrance into the petiole it 
respectively, the typical ““H” of Diplolabis and the “‘dumb-bell”’ of 
M sacepeydropi The changes in structure presented by the foliar bundle as 
s from node to petiole, and the striking similarity at the base of the 
pe tax between these two species, and indeed among all the Zygopterideae, 
furnish further evidence of the conservatism of this region and of its importance 
as a seat of ancestral characters.—E. W. SINNOTT. - 
1% Gorpon, W. T., On structure and Dane af Diplolabis Rémeri (Solms). 
Trans. Roy. ce Edinburgh 47':711-736. pls. 
structure and affinities of ul Raghanti duplex (Williamson). 
Trans. Roy: Mes Edinburgh 48':163-190. pls. I-4. 1912. 
