CHAP. VII. 
DISENGAGEMENT OF CALORIC. 
333 
than in Arums; and it is here that the most remarkable 
degree of developement of caloric has been observed. Sene- 
bier found that the bulb of a thermometer, applied to the 
surface of the spadix of Arum maculatum, indicated a tem- 
perature 7° higher than that of the external air. Hubert 
remarked this, in a still more striking degree, upon Arum 
cordifolium, at the Isle of France. A thermometer placed in 
the centre of five spadixes stood at 111°, and in the centre 
of twelve at 121°, although the temperature of the external 
air was only 66°. The greatest degree of heat in these ex- 
periments was at sunrise. The same observer found that 
the male parts of six spadixes, deprived of their glandular 
part, raised the temperature only to 105° ; and the same 
number of female spadixes only to 86° ; and, finally, that 
the heat was wholly destroyed by preventing the spadix from 
coming in contact with the air. 
Similar observations were made by others, with corre- 
sponding results ; but, nevertheless, as many persons attempted 
in vain to witness the phenomenon, it began to be doubted, 
especially after Treviranus added his authority to that of 
those who doubted the existence of any disengagement of 
heat. The truth of the statement of Saussure and others 
has lately, however, been placed beyond all further doubt, 
by the experiments of Adolphe Brongniart upon Colocasia 
odora. [Nouv. Ann, du Museum, vol. iii.) From the period 
of the expansion of the spathe, he applied to the middle of 
the spadix a very delicate and small thermometer, which he 
fixed to its place by a piece of flannel rolled several times 
round it and the spadix, so that the bulb of the thermometer 
touched the spadix on one side ; and on all others was pro- 
tected by the flannel from contact with the air. All this 
little apparatus covered so small a portion of the spadix, that 
it was left in its place without interfering with the functions 
of that part. On the 13th of March, the spathe not being 
open, the flower diffused, notwithstanding, a fragrant smell. 
On the 1 4th it was open, and the odour w^as much increased. 
The emission of pollen took place on the 16th, between 8 
and 10 A.M., and continued till the 18th. On the 19th the 
