424 W. P. Wilson-—Respiration of Plants. 
When plants are + Pee of every trace of free oxy gen by 
placing them in atmosphere of nitrogen or of hydrogen, 
they still slaere so long as life exists, to excrete carbonic 
acid. The discovery of this fact, which has been observed for 
animals as well as cian . not of recent ice although its 
signification was only recently understood. As early as 1798 
Rollo* observed that barley, which had been wet for two days 
and then placed in a vacuum, excreted carbonic acid; and that 
at the end of twelve days, the amount equaled six ‘times the 
volume of the barley. 
Saussure} placed plants in an atmosphere of nitrogen to see 
if they would grow, and found that they excreted carbonic 
acid, Thich he remarks must have been produced at the ex- 
pense of the substance of the plants 
At a still later date Bérard,t abi experimenting on the 
preservation of fruits, placed green pears in a vacuum an 
ey rved for several days following an excretion of carbonic 
a 
 Biouphton§ and also W. Pfeffer] have recorded the same 
phenomenon in plants deprived of free oxygen 
In 1875, Pfliiger§/ obtained some very interesting results in 
animal respiration while experimenting on frogs. These animals, 
carbonic acid as if they had been placed in pure oxygen. In 
another of Pfliiger’s experiments, a frog continued to give off 
carbonic acid during eleven consecutive hours, and at the end 
one sn 
the expiration of carbonic acid in the absence of free oxygen, 
take place in the cells. He named the process intramolecular 
respiration 
n 1878 a critical résumé on the aoe and signification of 
sespifation in plants,** written by W. er, brought together 
all the then Vow ‘facts which could ba made to bear on this 
subject. The similarity existing between animal and plant 
respiration was sharply noted, and the term ¢ntramolecular 
respiration, taken from Pfliiger, was made to cover a like series 
of phenomena i in plant life, viz: the chemical changes continu- 
* Annales de Chimie, 1798, vol. xxv, p. 42. 
+ Recherches sea 1804, p 
$ An de Chim) pte aad a vol. xvi, 1821, p. 174. 
6 
Arbeit. d. Warzburger Tustituts, 1871, Bd. I, p. 34. 
{ Archiv. fir Physiolo gie, Bd. + 1875, p. 313. Pfliiger gives other refer- 
ences to investigators in animal Ls sonaticad who had made similar experiments on 
cae we _ — the 18th century. 
ie Bede shraar: der Pi eye in der Pflanze, Landwirth- 
achattiche Jahrbiicher, 1878, Bd. VII, p. 
