380 FREAKS OF PLANT LIFE. 



Dr. De Vriese has also referred to a high tempe- 

 rature obtained at Burtenzorg, in the male cones of 

 Cycas circinalis, but does not state the precise amount ; 

 he says that the elevation always took place between 

 six and ten p.m., and was accompanied by a strong 

 smell. 1 



The evolution of heat in other plants, where the 

 flowers are produced singly, and not enclosed in a 

 spathe or envelope, is not only less, but more diffi- 

 cult of determination than in agglomerated flowers. 

 Wherever a number of flowers approximate, as in 

 composite plants, greater heat has been detected. 

 Amongst the species which have been tested may 

 be mentioned the flowers of a Cistus, in which three 

 degrees were registered above the surrounding air. 

 In geranium as much as six degrees are said to have 

 been determined. Saussure found by a thermometer 

 — scarcely a satisfactory medium — that the tuberose 

 rose half a degree, the flowers of a gourd from 

 i° to 3 Fahr., and a Bignonia only i°. The 

 flowers of Victoria regia were tested at Hamburg 

 when the temperature of the house was 70 7' Fahr., 

 and the flowers found to be 8o° 3'. On another 

 occasion, when the air was 72° 5', the flower had risen 

 to 105° 1', or the rather extraordinary increase of 

 about 33 . 2 If this determination is an accurate one 



1 Hooker's " Kew Gardens Miscellany," iii., p. 186. 



2 Balfour's " Class Book of Botany," p. 519. 



