306 The Botanical Gazette. — 
to increase transpiration. This Jumelle considered to be 
to the fact that the anzsthetic, by affecting the chloroplast 
stopped assimilation; thus more of the energy of the absorks 
light ray was used in chlorovaporization. In the dark 
Jumelle found that the anesthetized plant lost less water the 
the normal plant, but failed to come to any definite decision 
as to why this should be so. i 
MM. Verschaffelt® criticised M. Jumelle’s methods of 
perimenting, and questioned his conclusions in regard to 
relation of,carbon dioxide to evaporation in the light and 
the dark. They used in their investigations a modificat 
of the Kohl transpiration apparatus. The modification « 
sisted simply of a glass vessel containing culture fluid or watt 
into which the roots, or in some cases the cut end, of the rs 
extended. The evaporation was measured by the los ® 
weight of the apparatus; of course no water could escape ¢ 
cept through the plant. In the case of assimilating plants! 
water evaporated was collected by calcium chloride. : 
was because the Verschaffelt brothers considered that the 
crease in weight of the plant due to assimilation must 
taken into account. They concluded that the transp 
of a plant inan atmosphere free from carbon dioxide ad 
than in air containing it, both in the light and heel 
Further, that the presence of carbon dioxide in th mire 
creases evaporation in the light independently wie 
M. Jumelle made a critical discussion of t ai 
tions and not only proved the correct | 
results but also aes where the MM. Verschaftelt 
their mistake. tne the 
This article is followed by a final one® sed . 
further investigation of the points in ponies a gmt 
sults fully confirmed Jumelle’s former woe in 
that, in the light, the presence of carbonic ac! oF me 
around the plant devoid of chlorophyll has no ¢° 
piration. The influence of carbonic sti 
Clusively upon chlorophyllian transpiration. ied to 
The Spacdiee of acesaite acid gas from air supplied “ 
«al 
*Bot. Centralb. xi (1890). 373-374- 
TRevue gén. de Bot. 1891. nos. 30 aud 31. 
*Revue gén. de Bot. Juillet 1891. 
