304 



LECTURE XIV. 



By means of an apparatus similar to the above figure, Goppert deter- 

 mined the excess of the temperature among the seeds over that of the 

 surrounding air in the following cases : 



Wheat and Oats 



Peas and Hemp 



Maize 



Clover 



Sfiergula arvensis 



Brassica Napus 



Carum Carui 



11-25 12-50 C. 

 7-50 875 

 6-25 7-50 



17-50 



11-25 



21-25 

 7-50 



The evolution of heat in connexion with flowering appears 

 to have been first observed by Lamarck in the case of the 

 spadix of Arum italicum, and it is with compact inflores- 

 cences of this kind that most of the subsequent observations 

 have been made. Senebier was the first to determine by 

 means of the thermometer the difference between the tem- 

 perature of the spadix and that of the air. 



The following is a series of determinations made with Arum macu- 



latum : 



A striking illustration of the dependence of the evolution 

 of heat upon destructive metabolism is afforded by the fact 

 that the evolution of heat and the absorption of oxygen are 

 intimately connected. Hubert observed that when the 

 spadix of Colocasia odora was smeared with oil or with 

 honey, that is, when the free access of air was prevented, 

 its temperature sank ; Vrolik and de Vriese could detect no 

 rise of temperature in the spadix of Colocasia odora in an 



