or 3O. No variation in the results occurred, whe- 

 ther the experiments were repeated in a dry room, 

 or under the shade of thick and humid trees. 



171. M. Hubert next endeavoured to ascertain 

 the part of the spadix to which this increase of tem- 

 perature was owing. He had found that the medul- 

 la, or pith, raised the thermometer, when plunged 

 into it, in the same way as the exterior surfaces had 

 done ; but reflecting that the heat of the pith might 

 arise only from the exterior surface, he removed this 

 latter from four spadices without touching the me- 

 dulla. These medullas were then tied round a ther- 

 mometer, which, at sun-rise, was at 17, but no sign 

 of increased temperature occurred during 24 hours, 

 and the uncovered spadices withered towards the mid- 

 dle of the day. At the same time, he tied the remo- 

 ved surfaces of the spadices round the bulb of ano- 

 ther thermometer, and it rose to 39. This he re- 

 peated several times, which convinced him, that this 

 singular faculty is possessed by the exterior surfaces 

 of the spadices, and within the thickness of ~ of an 

 inch at most. If the spadices of the plant were di- 

 vided some time before the development of this 

 heat, the fluid that escaped from the divided portions 

 was colourless, which is not the case when the heat 

 has been previously given out. 



172. Lastly, M. Hubert made experiments to dis- 

 cover the circumstances necessary to the production 

 of this great increase of temperature. He found 

 that if the spadices were closely coveivd with a cloth 

 dipped in olive oil, grease, or tallow, no increase of 

 temperature took place : and that if, at their highest 

 temperature, they were plunged into cold ivater, 



