300 THE SCHOOL OF REAUMUR 



digression in these words : — " While I was engaged 

 upon the dragon-flies, I accidentally caught sight of the 

 winged fruits of the sycamore. It struck me that there 

 was a resemblance between the wings of plants and the 

 wings of insects. Since some writers had compared 

 insects and plants without noticing this point, I thought 

 it might not be disagreeable to my readers if I were to 

 ofi"er my reflections thereupon." 



He figures the winged fruit of the sycamore, the 

 winged seeds of pines, and the plumed fruits of several 

 composites. He shows that wind will carry them far 

 away, and hinder them from lying heaped about the 

 parent plant ; that the sycamore fruit and the pine seed 

 revolve as they descend, giving time for the wind to act 

 upon them ; and that the plumes which make up the 

 " Feder-Ballen " of a dandelion revolve as they drift 

 across the fields, bearing along the heavier fruits 

 which hang beneath. 



Freshwater Polyps 



Vol. Ill ends with a supplementary chapter entitled 

 Historie der Polypen der sussen Wasser und anderer 

 hleiner Wasserinsecten diesiges Landes. Eoesel begins 

 by telling us that when Trembley's discovery of Hydra 

 became known to him, he determined to procure fresh- 

 water polyps and study them. But diligent and long 

 continued search in the pools and streams of Bavaria 

 brought to light no Hydra until many years had 

 elapsed. Roesel's quest was not, however, fruitless. 

 Though he found no Hydra, he found many compound 

 animals which were new to him, and these he described 

 and drew. When he became paralysed, and unable to 

 leave his room, he sought to console himself with the 

 microscope, and sent out for a supply of pond vegetation. 



