TREMBLEY 283 



sters, seven-headed hydras, double hydras, in which one 

 body enclosed another, &c. He found it possible to 

 join up the fragments of different individuals. His 

 turning of a polyp inside out was a still more wonderful 

 feat. The base was pushed inwards until it emerged 

 through the mouth, a bristle being the only instrument 

 employed. The polyp had a great inclination to turn 

 itself back again, which Trembley sometimes prevented 

 by spitting it on a bristle. The most extraordinary 

 feature of the story is that polyps thus treated could 

 live, feed and bud out new individuals. For the truth 

 of his statement he appeals to the witnesses who saw 

 it done, to AUamand, professor of natural history at 

 Leyden, who successfully repeated the operation, and 

 indirectly to Lyonet, who made the drawings. How a 

 polyp so treated could digest its food is an unsolved 

 mystery, and naodern zoologists find it hard to believe 

 that there is not some mistake in the account. 



Baer ^ has remarked that Trembley's discovery appre- 

 ciably modified the teaching of physiology by showing 

 that an animal without head, nerves, sense-organs, 

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

 about. 



The Polype d'eau douce contains good figures of 

 another compound animal, the Polyzoan Lophopus, 

 which Trembley calls the " polype a pannache." 



Eight of the thirteen plates were engraved by Lyonet, 

 who was already a keen and experienced naturalist, 

 living at the Hague, and warmly interested in Trembley's 

 work. Though a skilful draughtsman, Lyonet had never 

 attempted to engrave, nor had he even seen how engrav- 

 ing is done. A Dutch engraver, Wandelaar, being struck 

 by the beauty of his drawings, persuaded him to try 



» Reden, Vol. I, pp. 109, 154. 



