Bet a al ae ees FR Ee Sg ee ES. ee 
SEE RN ae Sel Bae Se 
Esra ue : ios, 
1898] CURRENT LITERATURE 149 
of this important collection of North American plants and its deposit in the 
Academy of Sciences of Philadelphia is a matter of congratulation among 
taxonomists.—J. M. C 
Mr. Henry H. Dixon‘ has published recently some very interesting 
papers upon transpiration, which deal with the results of experiments which 
satisfy the author that transpiration is a “ vital”’ process rather than a physical 
one. By “vital” processes he means “those which cannot be accounted for 
by the immediate energy-relations of the organism to the external world, but 
those in which energy previously stored by the organism, ¢. g., oxidizable 
ne is utilized, and which only take place during the life of the organ- 
ism.’ uring transpiration, therefore, the elevation of water in the vessels 
resembles the raising of water in plants by root pressure. The phenomena 
of transpiration responded sufficiently to oxygen and to anesthetics to sug- 
gest that it is connected with vital phenomena. The conclusions drawn from 
experiments in a saturated atmosphere are as follows: 
1. The elevation of the water of the transpiration current, when the leaves 
are Surrounded with a saturated atmosphere, is effected by pumping actions 
ees | in the living cells of the leaves. 
e observations on the drying back of branches furnished with dead 
leaves renders it highly probable that these vital pumping actions are par- 
tially or wholly responsible for the elevation of water even in an unsaturated 
atmosphere. 
hese pumping actions are capable of raising the water against an 
external hydrostatic pressure. 
. In common with other vital actions, they are accelerated by a moder- 
ately high temperature, and are dependent on the supply of oxygen. 
5. The cells adjoining the terminal portions of the water conduits appear 
to possess this activity, and, in plants provided with water-glands, the pump- 
ing actions are not limited to the secreting tissues of these glands.—J. M. C. 
THE GENETIC RELATIONSHIPS between the phanerogams and cryptogams 
in the light of the most recent investigations are discussed by Belajeff.s As 
the title would indicate, the paper presents no new facts. Little attention 
is paid to the sporophyte, but the evolution of the male and female gameto- 
phyte, from the bryophytes to the spermatophytes, is presented in a masterly 
way. The female gametophyte shows a gradual transition from independ- 
ence in the bryophytes to complete dependence in the gymnosperms and 
angiosperms, and the archegonia which it bears show a gradual transition | 
from forms with the neck and venter free to forms with the entire archego- 
n the effects of stimulative and anzsthetic gases on transpiration, Proc. Roy. 
ish ey III. 4: 618-626, 1898; T em meee into a saturated atmosphere, /. c. 
627-635. 
5 Biol. Centralbl. 18 : 209-218. 1898. 
