292 The Botanical Gazette. [May, 
Five glass gasometers of 25’ capacity each were used, after 
being carefully calibrated for each half liter. Three of these 
were used for pure gases and two for mixtures. It was found 
very difficult to secure a definite mixture, say of two parts 
CO, and one part O, and impossible to maintain it for any 
length of time on account of the unequal absorption by the 
water. This led to the employment of paraffin oil as a protec- 
tion to the water. Eudiometric analysis showed that during 
twenty-four hours (the usual period for which a gasometer 
was used) no considerable alteration then occurred in the pei- 
centage composition of the mixtures. Gas analyses were 
made at frequent intervals to check errors. 
The gas chambers in which objects were observed were of 
the form used by Kny, round shallow brass boxes 38 X 18™ of 
30x 12™" with entrance and exit tubes at the side, having the 
bottom of thick glass and the top a metal ring, with cover- 
glass in the center, which screws on air-tight by means of an 
intervening washer. The object could then be placed in 4 
anging water drop on the under side of the coverglass. 
After discussing the sources of error, the author presents 4 
detailed account of his experiments, only the results of which 
can be here summarized from his own words. ; 
1. Pure CO,, if its action does not exceed a certain time 
variable in different cases, has a retarding influence upon té 
vital phenomena, but not a permanently injurious one. 
2. The retarding action of the CO, is not negative, due to 
the absence of oxygen, but a specific characteristic 
3. The CO, in many cases probably increases, 
rectly or indirectly, the extensibility of still growing mem: 
ranes. In many other cases when the extensibility 'S 
— it brings about a rupture of the membrane of living 
cells. 
4. Asmall amount of CO, (1-10 per cent. ) accelerates 
growth but does not raise the turgor-pressure of pollen-th nf 
which have been accelerated in growth. The turgor increas’ 
gradually if the pollen-tubes are, after a short exposure 
CO,, again exposed to atmospheric air. differ: 
5. Different cells of a plant are sensitive to CO, 11 di 
ent degrees. 
6. Living plant cells may become inured to the distut 
action of CO... The plasma is also capable of a certain 
gree of accommodation.—R. 
bing 
de- 
