CARBON MONOXIDE AND OTHER GASES 59 
so supported that there would be no danger of the potash 
“crawling” and reaching the young plants. The diminution in 
volume caused by the absorption of CO, was corrected by running 
in pure oxygen at intervals as required — usually twice every 
twenty-four hours. Thus the atmosphere (as repeated analyses 
showed) was kept at normal oxygen pressure and the CO, being 
so very slightly soluble in water, did not diminish perceptibly. 
The same is also true of the illuminating gas experiments. In all 
respects, even to the mechanical manipulation, the controls were 
treated in the same way as the experiments with the gases. All 
of the plants had equal illumination, and while of course in the 
Winter time some etiolation is unavoidable, the conditions of the 
bell-jars were precisely similar in any one experiment. 
A list of the seedlings on which experiments have been com- 
pleted, up to date, is as follows: Vicia faba, Zea Mays, Sinapis 
alba, Helianthus annuus, Triticum vulgare, Fagopyrum Fagopyrum 
and Oryza sativa. 
The effect of these gases on the condition and growth of the 
above-named seedlings may be considered under the following 
heads : (1) Growth in length ; (2) growth of secondary members ; 
(3) growth in thickness (primary) ; (4) growth curvatures ; (5) 
formation of chlorophyl. It is to be understood that in all of the 
experiments of this series the nitrogen of the air was replaced with 
either CO or illuminating gas (referred to hereafter merely as 
gas”). 
Under the first head we may take up for consideration a con- 
siderable number of measurements which have been made. These 
measurements are of the length of the primary root and of 
the Shoot, or in the case of the monocotyledonous forms of the 
di Stance from the seed to the tip of the longest leaf. There is 
shown in general to be a very clearly marked retardation, which 
Must finally amount to a toxic effect, in both CO and gas. Taking 
© average of three experiments with Vicia, each experiment 
being in itself an average of from 8-10 individuals, we find the 
*PProximate ratio of the length of the shoot about as follows : 
© Normal being 25, in CO it is 15, and in gas only 10; while a 
ag comparison of the length of the primary root gives the fol- 
Owing ratio: control 30, in CO 12,in gas 10. Corn seedlings 
