22 COMPARATIVE ANATOMY HKIXWK Cl'YIKR 



homologises the stages of the frog's development with the 

 Ei;g, the Worm, and the Nymph of insects (I>ook of Nature, 

 p. 104, Eng. trans., 1785). He even speaks of the human 

 embryo as being at a certain stage a Man-Vermicle. 



In the 1 8th century, Reaumur and Bonnet continued the 

 minute study of insects, laying more stress, however, on their 

 habits and physiology than upon their anatomy. Lyonnet 

 made a most laborious investigation of the anatomy of the 

 willow-caterpillar (1762). John Hunter (1728-93) dissected all 

 kinds of animals, from holothurians to whales. His interest 

 was, however, that of the physiologist, and he was not specially 

 interested in problems of form. It is interesting to note a 

 formulation in somewhat confused language of the recapitula- 

 tion theory. The passage occurs in his description of the 

 drawings he made to illustrate the development of the chick. 

 It is quoted in full by Owen (J. Hunter, Observations on 

 certain 1 \irts of the Animal (Economy, with Notes by Richard 

 Owen. London, 1837. Preface, p. xxvi). We give here 

 the last and clearest sentence " If we were to take a series of 

 animals from the more imperfect to the perfect, we should 

 probably find an imperfect animal corresponding with some 

 stage of the most perfect." 



The tendency of the time was not towards morphology, 

 but rather to general natural history and to systematics, the 

 latter under the powerful influence of Linnaeus (1707-1778). 

 The former tendency is well represented by Reaumur 

 (1683-1757) with his observations on insects, the digestion 

 of birds, the regeneration of the crayfish's legs, and a hundred 

 other matters. To this tendency belong also Trembley's 

 famous experiments on Hydra (1744), and Rosel von 

 Rosenhof's Insektenbelustigungen ( 1 746- 1 76 1 ). 



1!' iniiet (1720-1793) deserves special mention here, since 

 in his Traitc d'lusectologic (1745), and more full} 7 in his 

 Contemplation dc la Xatiire (1764), he gives the most com- 

 plete expression to the idea of the /:>//<//< des ctres. 



This idea seems to have taken complete possession of his 

 imagination. He extends it to the universe. Every world 

 has its own scale of beings, and all the scales when joined 

 together form but one, which then contains all the possible 

 orders of perfection. At the end of the Preface to his Traitc 



