96 



howtner, will not do this when they are immersed in water. Init it is 

 necessary to set u\> ratlier ((miiilirated aiii)arati'.s." 



Doctor GaiK'ii,^'. who may he regarded as an autliority in jilant physi- 

 ologj', in commentimi^ on tliis experiment criticises severely the statement 

 tiiat kind plants may he used. He says, "An erroneous exi>eriment, given 

 in several text-hooks, accompanied liy a false illustrati<m, is that one in 

 which leaves of land plants placed under water are represented as giving 

 off buhbles of oxygen which rise through the water. It is true that leaves 

 which are enveloped in a tilm of air do cair.v on some jihotosynthesis under 

 water, but the amount is so .small that it is doubtful if any visible bubbles 

 of oxj'gen are relea.sed. the tiny quantities being taken directly into 

 solution.'"* 



It is the iiurpose of this paper to show that some land plants do carr.v 

 on photosynthesis, when submerged in water, and that for puri)oses of the 

 experiment described aI)ove. are even better thiui the water plants ordinar- 

 ily used. 



In September of 1011 my attention was callecl to the fact that .1/'//- 

 lofus alha, when submerged in water, could carry on photosynthesis, with 

 considerable evolution of gas, and that the gas is iiarticularly rich in 

 oxygen. At the suggestion of Professor Howard J. Banker a number of 

 simple pi'eliminary experinients were carried on to test the power both in 

 Melilotus and in several other land plants. It was intended that more 

 careful exiieriments should be performed later to determine the i>ercentage 

 of oxygen in the gas and the rate of the evolution of the oxygen under 

 varying ccmdilious. While tliis (pnintitative work has not been done, the 

 results so far ol>(ained are so striking as to appear of interest and worthy 

 of note. 



In the expei'iments as pcrrormed. a few leaves of the plant under 

 observation, were placed in the usual manner in a glass fuiuiel which was 

 inverted in a large glass jar lull of wati-r. .\ test tube of .'^.Ui-e. capacity 

 was used t<> collect the e\()lved gas. Carbon dioxide was generated by 

 treating ordinar.v limestone with hydrochloric acid, and ;i stream of this 

 gas W.MS kept hubhling tlirougji the water outside the funnel. TIu' whole 

 ajiparatus was exjioscd to sunlight in .a south window. 



With M(lili>lii\ (illiii. usiuLT llii-ee or lour vigorously growiui,' shoots, 

 having approximately one hundred leaves, fi-om CO to sOcc. of gas wa.> 



Mliiiion};, A I.nliin.ilorv ('Diusr in I'laiU I'li,vsii)li(i;y. p. 1l»:!. 



