424 BOTANICAL GAZETTE [NOVEMBER 
to a purely physical change, perhaps a temperature change. Some will object 
to the distinction between physical and physiological changes, for is not the 
latter, as well as its physical aspects, largely unknown? In this connection it 
might be mentioned that we know little about the effect of light upon “hydra- 
tion”’ of colloids in general, and of cell colloids especially. Recently we have 
been coming to see that this is quite as important in growth as is turgor pres- 
sure.—WILLIAM CROCKER. 
Embryo sac of Myosurus.—In 1913 NAWASCHIN and FINN” concluded 
that chalazogams are primitive and derived from gymnosperms, the conclusion 
being based largely upon the reduction series shown by sperms. They found 
that the generative cell of Juglans reaches the embryo sac as a binucleate 
cell, which means that nuclear division had occurred, but that distinct male 
cells had not been organized. This condition, carried over from gymnosperms, 
was regarded as an intermediate one between a well developed sperm and a 
naked sperm nucleus. TCcHERNOYAROW” has now found the same condition 
in Myosurus minimus, and concludes that this is probably a feature of the 
“Polycarpicae,” and that this phylum and the chalazogams are two inde- 
pendent primitive branches from the gymnosperm stock. The paper also 
contains a detailed account of the events from the development of the pollen 
tube to the act of fertilization. In general the events are of the usual kind, 
but attention may be called to the fact that the author lays special stress upon 
the idea that there is some coordination which assures the mek ccpenre ck of the 
pollen tube at the moment of maturity of the embryo sac. C. 
Northern plains forests of Canada.—A recent report by CONNELL® deals 
with the forest region lying north of the prairies in Manitoba, Saskatchewan, 
and Alberta. It extends from the contact line with the Laurentian pine plain 
near Lake Winnipeg in the east, to the Rocky Mountains in the west. The 
northern limits are not determined. If the portion of northern Alberta most 
carefully studied be taken as typical of the entire region, it is made up as 
follows: (1) boulder clay slopes, which comprise about 50 per cent of the area, 
more than half of these slopes being covered with a poplar association, a little 
less than one-fourth with a mixed spruce-poplar forest, and less than 2 per cent 
with a pure spruce association; (2) sand ridges, which amount to 18 per cent 
of the area and are covered with nearly pure Pinus Banksiana, P. Murrayana 
appearing in mixture with it in the western portion of the region; (3) swamps, 
which occupy the remainder, showing how poorly developed the drainage is. 
In the swamps there is a stunted growth of Picea mariana and Larix laricina, 
the former predominating.—Gero. D. FULLER. 
* Rev. Bor. Gaz. §7:162. 1914. 
* TCHERNOYAROW, M., Les nouvelles données dans Vembryclogie du Myosurus 
minimus L. Mém. Soc Ne. Kiew 24:95-170. 1915. 
23 CONNELL, A. B., Some aspects of the nothern plains forest region of Canada. 
Forestry Quarterly 13:31-34. 1915. 
