86 PROCEEDINGS OF SOCIETIES, 
electrical apparatus, whether the spadix of Arum maculaium exhibited any 
development of heat at the period of flowering, as had been first observed by M. 
Brongniart, and subsequently by MM. Van Bsek and Bregsma, in Colocasia 
odora. The following is the account given by M. Dutrochet. The massive 
summit of the spadix of Arum maculaium begins to afford a heat greater than 
that of the surrounding air, about two days before the opening of the spathe. 
This heat encreases by little and little, until the spathe opens; then it exceeds 
that of the atmosphere by 11° to 12° centig., and continues so for about two 
hours, when it diminishes gradually, and disappears in about twelve hours. 
At a subsequent meeting, M. Dutrochet communicated some new observa^ 
tions on the development of heat in the flowering of Arum maculaium . His 
former observations had reference to the superior part of the spadix: he now had 
to allude to the development of heat, by the male and female flowers occupying 
the lower part of the spadix. The heat of the superior part of the spadix ,is at 
its maximum when the expansion of the spathe is completed; at the same time 
the heat of the male and female flowers is also at its maximum, but not so 
elevated. The heat of the superior part of the spadix disappears in the night 
of the day it blows, while that of the male and female flowers continues, but in 
a diminished degree, and again rises on the following day, even beyond the former 
degree. The heat diminishes from the top to the bottom of the spadix, and in 
all parts it diminishes in the night and increases in the day. This diurnal 
paroxysm has also been observed in flolocasia odora , by MM. Van Beek and 
Bregsma. 
Since the above communication was made, a note has been addressed to the 
Editor of Id Institute from M. Bory de St. Vincent, stating that it was not 
M. Ad. Brongniart who first observed the development of heat in Colocasia 
odora. That MM. V an Seek and Bregsma should not have noticed what he 
had written on the subject in 1804 , or the title of the French to the discovery, 
he says, is not surprising; but that such a deficiency of botanical erudition 
should be exhibited in Paris, requires explanation. As early as 1777, Lamarck 
had announced the development of heat in Arum Italicum. In 1802 , M. B. de 
St. Vincent himself described Arum cordifolium (since called Colocasia odora), 
and noticed the manner in which the development of heat was discovered, with a 
long series of observations by M. Huber ; and ten years afterwards, in his 
account of a voyage to the four islands of the African seas, from analogy souglit-for 
and discovered an extraordinary development of heat in Arum esculentum , as 
well as in the anthers of other plants ; he also observed, that the odour exhaled 
by these plants was perceived during the period of heat. 
