618 
ME. J. BEOUGHTON ON A CEETAIN EXCEETION OF 
plant varies very considerably. Generally speaking, it seems to be greater according to 
the activity of the plant’s growth. It is also given off at a greater rate when the tempe- 
rature is increased. Daylight also has a stimulating effect, which is sometimes very 
marked, and is irrespective of temperature*. 
The phenomenon is entirely dependent on the life of the tissues. Causes which 
arrest life also arrest the exhalation of carbonic acid. Immersion in water at 60° C. for 
two minutes entirely deprives the part of the property, whether it be bark, leaves, flower, 
or roots. Sadden drying in vacuo over sulphuric acid has the same effect, even when 
the plant is allowed to imbibe water till it has the appearance of life. In both cases it 
will remain for days without gas appearing in the eudiometer. Even living parts of 
plants in a state of rest give off no gas. Such is the case with the tuber of a potato. 
It will be observed in the foregoing tabular statement that in most cases nitrogen 
gas is also given off. In the greater part of these it is due to the tissues of the plant 
containing air. This was experimentally proved in the case of the phyllodes of Euca- 
lyptus globulus. It will be seen in the Table that 5 grms. of these gave off T60 cub. 
centim. of nitrogen. But when the phyllodes were put into a vessel connected with 
the mercurial pump in the manner before described, and thoroughly exhausted, the gas 
subsequently exhaled was pure carbonic acid. In some other cases it was found impos- 
sible to introduce leaves &c. into the eudiometers without some adherent air, and hence 
the source of nitrogen. But from Fescue grass nitrogen was actually evolved in con- 
siderable quantities. It was remarked that the grass altered its colour in the eudio- 
meter, and, unlike most plants, suffered by the treatment to which it was subjected. To 
ascertain more fully the conditions of this exhalation of nitrogen, two similar bottles 
were filled with blades of the grass. One was placed in connexion with the Sprengel 
pump, the other served for occasional examination. The following numbers were 
obtained from 85 grms. of grass. 
Gas of day. 
Gas of night. 
Total gas. 
C0 2 . 
N. 
Total gas. 
C0 2 . 
N. 
54-5 
28-2 
36-5 
34-0 
38-5 
54-5 
26-79 
31-50 
26-73 
29-92 
0-00 
1-41 
5-00 
7- 27 
8- 58 
30-9 
24-2 
32*8 
46-5 
44-2 
30-9 
20-32 
27-67 
38-73 
35-91 
0-00 
3-88 
5-13 
7- 77 
8- 29 
No decomposition apparent. 
Faint smell of decay. 
Fermentation set in. 
Hence from grass it will be observed that the evolution of nitrogen continually in- 
creased in amount, and was coincident with the setting in of decomposition. I am I 
think justified in attributing the production of nitrogen to the breaking up of the nitro- 
genous constituents of the plant. The grasses are exceptionally unsuitable subjects for 
this kind of investigation, from the readiness with which they begin to ferment when in 
* Leaves immersed in carbonic acid have been shown by Boussingauxt (Compt. Eend. vol. Lx. p. 872) to 
have no power of decomposing the gas tinder the influence of light. 
