- 
W. P. Wilson—Respiration of Plants. 425 
ing to take place in the plant-cell after oxygen has been with- 
drawn, resulting always in the production of carbonic acid, and 
often in other more or less important products. In this article 
the author Jays great stress on intramolecular eta as being 
the first cause of the oxygen or normal respirati 
e next works of any special eu eine st plant 
respiration appeared in 1879.* ortmann measured and com- 
pa e carbonic oe expired from germinating plants placed 
in common air, wit 8 ven off from an equal number o 
co epee in a vacuu 
all the carbonic acid produced in plant respiration has its origin 
in intramolecular decompositions; or, in other words, that the 
free oxygen of the air cept no direct part in the formation of 
the at acid in respiratio 
made of the expir carbonic acid from the same ‘planta placed 
both in airand in hydrogen gas. Th thods of experimenta- 
n used were the following a constant current of air, previ- 
ously freed from carbonic acid, was passe y means of an 
aspirator, first through a large number of germinating seeds, or 
other objects to be experimented upon, and then thro ugh long 
tubes filled with barium hydrate in which the carbonic acid 
given off by the seedlings was absorbed, essentially ge accord- 
ance with . Pettenkofer's method.t After a given time had 
elapsed, hydrogen, as an indifferent gas, was hes to replace 
their. This was quickly done by exhausting the air in the 
seed-vessel and tubes leading thereto, and then introducing 
hydrogen to take its place. A constant current of hydrogen 
was then passed over the seedlings, Sieniaely as had been done 
previously with a 
The carbonic ‘oie was determined for either half hourly or 
hourly intervals. This was easily accomplished by using two 
* Wortmann, tiver die Beziehungen der intramolecularen zur oo Athmung 
der Pflanze, in "At beit d. Wiirzburg Instituts, 1880, Bd. IT, p. 5 
+ A mue ch shorter cbeebait than the present appeared in German in “ Flora,” 
st Avhandlangen der Akademie d. Wissenschaften in Miinchen, Cl. II, Bd. 1X, 
Abth. IT, p. 2 
