286 THE SCHOOL OF REAUMUR 



his chief thoughts to philosophy, and wrote much tW 

 was once highly esteemed, though it has failed to endure, 

 Bonnet and his wife (a daughter of the celebrated De 1 

 Rive family), being childless and wealthy, adopted a 

 nephew of Madame Bonnet, who made for himself aM 

 great name as a botanist, a geologist and an explorer of^ 

 Mont Blanc. This was Horace Benedict de Saussure, 

 (1740-1799). 



Experiments on Aphids 



To the Traite d/ Insectologie is prefixed a short intro- 

 duction, for which Reaumur's Histoire des InsecU 

 furnishes all the facts, and all the figures of insectsj 

 Bonnet then proceeds to explain the experiment pre 

 posed to him by Reaumur, and the measures taken 

 carry it out. He filled a flower-pot with earth, am 

 plunged into it a phial of water, intended to suppl] 

 the food- plant. A new-born aphis, whose birth h? 

 been observed, was placed on the plant, and all wf 

 covered up by a bell-jar, which was pressed into^ 

 the earth, so as to exclude other insects. An aphis 

 found upon the spindle-tree was selected for the first 

 trial, which began on May 20, 1740. Bonnet kept 

 an exact diary of his observations, which were made 

 hourly or oftener during the day ; a good lens was 

 continually employed. The aphis changed its skin 

 four times, and came to maturity on June 1, when the 

 first young one was born. By June 21 the unfertilised 

 female had produced 95 aphids, all born alive. She 

 was then accidentally lost, having by this time assumed 

 a peculiar shape (flattish, narrowed in front and rounded 

 behind), which Geoffroy had mistaken for the male 

 aphis, but which Reaumur had shown to indicate an 

 exhausted female. Next year the experiment was re- 



