﻿i82 . BOTANICAL GAZETTE [makch 



immediate evolution of CO^ when tubers were cut in Richards's 

 work (/. c, 1896, p. 544) should be explained in the same way. 

 CO3 diffuses through cork so table xl. 



much more readily than does O December 6. Elodea at 39-41' C. 

 that a great accumulation of it = 



within the tuber, to be set free ^ime 



0.070 

 0.085 



0.097 



0. no 



O.IIO 



from any exposed surface, seems 



. 4:30- 5*30 



hardly naturstl. Kolkwitz^^ finds 5:30-7:30 



that grain ground to meal, soaked o-^o-n -^o 



in alcohol, or heated to 100 C, 11:30- 1-30 



all processes calculated to kill it, 



still gives off a very appreciable amount of CO^. The behavior 



of Elodea sap might point in the same direction, though the 



consumption of large quantities of sugar, observed by Hahn in 



in the sap of Arum, demands a different interpretation. 



The evolution of CO^, not only as a phase of death, but as a 

 process continuing indefinitely after death, is another question on 

 which I have sought for light. Reinke^^ has said that in the pres- 

 ence of atmospheric O dead seedlings and leaves continue to 

 evolve CO^ at ordinary temperatures, and his statement that no 

 microorganisms are responsible for the phenomenon ought to be 

 reliable, Schlosing^^ and Berthelot and Andre ^^ have found CO3 

 given off at high temperatures, /o-iio^'C., under the most 

 various conditions. If these observations admitted of general 

 repetition, all of our determinations of dry weights would be 

 proven not to represent the entire solid matter of the plant. 



My experiments with Hg,- Cu, and Zn, w^hich seemed at first 

 to be the most striking proof of indefinite loss of CO 3 after 

 death, can no longer be- regarded as any positive evidence on 



5^R. KoLKWiTZ, Ueber die Athmung ruhender Samen. Ber. Deutsch. Bot. Ge- 

 sells. ig : 285-287. 1901. 



5=J. Reinke, Zur Kenntniss der Oxydationsvorgange in der Pflanze. Ber. 

 Deutsch. Bot. Gesells. 5: 216-220. 1887. 



53 T. SCHLOSING, Sur la combustion lente de certaines matieres organiques. 

 Comptes Rendus Acad. Sci, Paris 108:527. iS8g. 



s^Berthelot et G. Andre, Etudes zur la formation deTacide carbonique etl'ab- 

 sorption de Toxyg^ne par les feuilles detachees des plantes. Comptes Rendus Acad. 

 Sci. Paris 118:45-54. 1894. 



