bo PERIOD III. 



the zoophytes, and dispelled the false notion that corals 

 are plants, bearing flowers, fruits, and seeds. 



Baer 1 has remarked that Trembley's discovery 

 appreciably modified the teaching of physiology by 

 showing that an animal without head, nerves, sense- 

 organs, muscles, or blood may perceive, feed, grow, and 

 nove about. 



At the time when Trembley was demonstrating the 

 asexual propagation of Hydra, Bonnet (supra, p. 45) 

 was demonstrating the asexual propagation of aphids. 

 Both naturalists were natives of Geneva, and both, as 

 well as their associate Lyonet, were in a sense pupils 

 of Reaumur, who not only set them an admirable 

 example, but directed their attention to promising 

 researches and discussed with them the conclusions 

 which might be drawn. Reaumur's experience had 

 seemed to confirm Leeuwenhoek's statement (supra, 

 p. 34) that aphids produce young alive, even though 

 no males are to be found among them ; but unlucky 

 accidents defeated his intention to confirm it by experi- 

 ment, and when Bonnet asked him to suggest a piece 

 of work Reaumur gave him the aphid problem. 2 



Bonnet filled a flower-pot with moist earth, intro- 

 duced a food-plant together with a single new-born 

 aphid, and covered all up with a bell-jar. In twelve 

 days the aphid produced its first young one ; in a month 

 ninety-five had been born from the same unfertilised 

 parent. As many as five generations were obtained 

 without the intervention of a male, each successive 

 parent having been isolated from the moment of its 

 birth. It was, however, discovered, apparently by 



1 Reden, Vol. I., pp. 109, 154. 



2 Trait^ d ' Insectologie, premiere partie. Two vols. 12 mo. 

 Paris, 1745. 



