374 FREAKS OF PLANT LIFE. 



are equivalent to decomposition, in which oxidation 

 takes place, and heat is evolved during the process. 



We are chiefly concerned here in the phenomenon 

 of the evolution of heat at the time of flowering, 

 for although, as in the case of germination, it 

 undoubtedly takes place, more or less, in all plants, 

 it is only under favourable conditions that the 

 temperature is raised to an appreciable extent. The 

 most suitable condition for observing the heat 

 evolved during germination is when a large number 

 of seeds are collected together ; so, also, the most 

 favourable condition for the determination of the 

 amount of heat evolved at the period of flowering is 

 when a large number of flowers are associated 

 together. This will account for the high temperature 

 determined in certain plants to be presently alluded 

 to, the results being proportioned to the number of 

 associated flowers. 



The evolution of heat at the time of flowering has 

 been observed most frequently, and with the greatest 

 satisfaction, in plants of the arum family, in which a 

 large number of flowers are collected together at the 

 base of the spadix, and these are surrounded by and 

 enclosed within an envelope, or spathe, which prevents 

 the rapid dissemination of the heat engendered. This 

 structure is sufficiently represented in our common 

 indigenous Arum maadatum, called " Lords and 

 Ladies," for illustration (fig. 83). This phenomenon 



