CHAP. V. DISENGAGEMENT OF CALORIC. 277 



spadix of Arum maculatum, indicated a temperature 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 experiments was at sun- 

 rise. The same observer found that the male parts of six 

 spadixes, deprived of their glandular part, raised the tem- 

 perature only to 105°; and the same number of female spa- 

 dixes 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 correspond- 

 ing results ; bvit, nevertheles, as many persons attempted in 

 vain to witness the phenomenon, it began to be doubted, 

 especialty after Treviranus added his authority to that of those 

 Avho doubted the existence of any disengagement of heat. The 

 truth of the statement of Saussure and others has lately, how- 

 ever, 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; 

 on all others was protected 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 March, the 

 spathe not being open, the flower diffused, notwithstanding, a 

 fragrant smell. On the 14th, it was open, and the odour was 

 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 flower began to fade. From the 14th to the 

 19th the temperature increased daily, during the night and in 

 the morning falling back to nearly that of the surrounding air. 

 The maximum of elevation of temperature above that of the 

 atmosphere occurred, — 



T .3 



