THE VEGETABLE KINGDOM. 461 



are opened the plants appear to suffer a febrile excitement. 

 Unwonted movements are observed in their floral organs, 

 and the temperature is sometimes raised in a very remark- 

 able manner. It seems, as the physiologist Burdach says, 

 that at such moments the plant issues from its humble 

 sphere and shows us traces of animal life. The stamens 

 are agitated, and quit their places, bending towards the 

 stigmata. More rarely, as if modesty were inherent in 

 the delicacy of flowers, the pistils advance towards their 

 spouses. 



By means of thermo-electric needles it has been proved 

 that the elevation of temperature in the flower is a wide- 

 spread phenomenon. In some plants this heat is so great 

 that an instrument of accuracy is not requisite to show it ; 

 the simplest thermometer suffices. It is only necessary to 

 touch even the flower in certain arums to observe that it is 

 of a burning heat, and we are astonished that it can sup- 

 port such a temperature without being consumed. De Can- 

 dolle observed that a thermometer plunged into the spathe 

 of an Italian arum rose to 143 36' Fahr. 1 



From the remotest antiquity men seem to have under- 

 stood the mysterious loves of plants. The question was 

 practically solved, for Herodotus tells us that the Babylo- 

 nians knew how to distinguish male from female date-trees, 



1 It was Lamarck who discovered that the flower of the arum gives out consid- 

 erable heat at the time of fecundation. De Candolle verified this fact at Mont- 

 pellier. It is a very remarkable phenomenon. I observed that at a certain 

 moment the flowers of some Colocashc grew so warm that their heat was felt by 

 the fingers of those who touched them. In other flowers the phenomenon is less 

 evident, still it is general. Brongniart, Dutrochet, Biot, and Schultze have rec- 

 ognized it by means of thermo-electric needles. 



