1913.] PUBLIC D()d'MP:NT — No. 31. 59 



correspond to the normal atui()Hi)lu'ric presMuro. Aecordino- to 

 Jaccard, a decrease in the })ressiire of oxyucn gives rise to an 

 accelerated growth and more profuse branching of the axis and 

 roots, together with an increase in the size of the leaves. The 

 water containing gas is taken np in small quantities by the roots 

 and translocated to the stem and leaves, and since plants possess 

 considerable power of accommodation they can do this for quite 

 long periods without injury. 



Plants, like animals, respond to stimuli arising from various 

 causes, and while plants may not respond as quickly as animals, 

 their sensitiveness is in many instances more acute. Specific 

 stimuli give rise to definite responses, and the nature of the re- 

 sponse usually corresponds with some immediate need of the 

 organism. The presence of water charged with gas in the plant 

 tissues stimulates the demand for oxygen, which is manifested 

 in a greater root development and leaf surface. 



Man and animals respond characteristically when subjected to 

 a decreased oxygen supply such as is caused by unusual exer- 

 tion like mountain climbing, running, etc. Dogs open their 

 mouths, run out their tongues and breathe more rapidly when 

 excited, and this is in reality a response to the demand for 

 more air or oxygen. In the same way, the increased size of 

 lenticels is a direct response to the demand for oxygen, although 

 in the case of both animals and plants it is purely reflex and 

 involuntary. 



Illuminating Gas as a Factor in Forcing the DEVELor- 

 MENT OF Plants. 



The stimulating effects of gas-charged water on willow cut- 

 tings led us to experiment with illuminating gas in other ways, 

 therefore a number of experiments were made to determine the 

 effects of atmosphere charged with the gas on the development 

 of dormant willow cuttings. Ether and other substances have 

 been used to stimulate plants in a dormant condition, and we 

 wished to learn whether gas would have the same effect. 



The willow cuttings were placed under sealed bell jars in 

 vessels of water and subjected to an atmosphere of illuminating 

 gas for twenty-four, forty-eight, seventy-two, ninety-six and one 

 hundred and twenty hours, respectively. A number of cuttings 



