﻿172 



BOTANICAL GAZETTE 



[march 



''experiment" bottle contained rather less Elodea, uninjured, in 

 150^*^ distilled water. The sap was extracted ^nd fltered during 

 the evening, and evolved a great deal of CO 3 during the night. 

 The record begins the next morning. 



This shows an acceleration of the evolution of CO^ from the 

 sap, caused by the cadmium salt; also from the sound plants, 



TABLE XXIX. 



May 23. " Respiration " by sap 



Time 



Experiment 



9: 40-1:22 



A slight precipitate in t 



1:40-6:34 



6:34 



1000 



6:34-7:34 



0.040 



he sap caused m 



0.046 



Cd(N03)3 in b 



Control 



0.08 



■^ 

 ^ 



0.261 



e to refilter it 



0.155 



oth bottles, 

 o.^io 



but not quite as much 



during the one hour 



of the action of the 

 cadmium. 



But the most re- 

 markable thing about 

 this experiment was 

 the great evolution 

 of COg from the fil- 

 trate. The filtration 

 seemed thorough both times, and after the second no precipitate 

 could be detected before the cadmium was put in ; afterward a very 

 slight one was formed. The filtrate was colored and opalescent 

 from the start. It is as impossible to treat the influence of cad- 

 mium on the evolution of CO3 from the sap as depending on the 

 carbonates in the latter as to suppose that the action of copper 

 on the sound plants depends on the protoplasm. If there are 

 processes going on in the sap which lead to the freeing of C0>^, 

 the cadmium may very well act on these processes. By the 

 duration and amount of this evolution the possibility of its being 

 an inorganic reaction is precluded. It suggests very strikingly 

 the accelerated respiration resulting from mechanical injuries, 

 on which we are well informed by the work of Stich ^^ and 

 Richards.*^ But nothing hitherto known would indicate that 



ere might be such a reaction by filtered sap. An identical 

 performance observed by Hahn **7 in the sap of the spadix of 



^s Stich, Die Athmung der Pflanzen bei verminderter Sauerstoffspannung xind 

 bei Verletzungen. Flora 74:1-57. 1891. 



"♦fiH.M, Richards, The respiration of wounded plants. Annals of Botany 10: 53^ 

 -582. 1S96. 



*7M, Hahn, Chemische Vorgange im zellfreien Gewebsaft von Arum maculatiun. 

 Ber. Deutsche Chem. Gesells, 33:3555-3560, 1900. 



th 



