134 NATURAL HISrOEY OF 



ingenuity. 1. Cutting off a polypes head. 2. Cutting 

 a polyp in two pieces. 3. Cutting a polyp in three 

 pieces. 4. Cutting the head of a polyp in four pieces. 

 5. Cutting a young polyp in two pieces whilst still 

 hanging to its parent. 6. Slitting a polyp open and 

 cutting off the end of its tail. 7. Cutting a polyp with 

 four young ones hanging on it. 8. Quartering a polyp. 

 9. Turning a polyp inside out. 10. An attempt to 

 make the divided parts of different polyps unite. 11. 

 A young polyp becoming its parent's head. This is a 

 course of torture sufficient to satisfy the most deter- 

 mined vivisectionist. Baker, not satisfied with sug- 

 gesting the course, has elaborately described and figured 

 the different stages of the experiments. 



Mr. Dunkerley, of Manchester, has recently suc- 

 ceeded in most of these experiments, including the 

 ninth. He informs us ("Microscopical News," October, 

 1883) that the hydra will sometimes turn itself inside 

 out of its own accord, and that he himself has effected 

 this result. Whether the hydra reversed the process 

 afterwards, we are not told ; but this is highly probable, 

 as a continual reversement would imply an exchange 

 of functions of the ectoderm and endoderm cells. 



The hydra was discovered by Leeuwenhoek in 1 703, 

 and an anonymous Englishman communicated a similar 

 discovery to the Royal Society about the same time. 

 It was not much noticed, however, till Trembley's 

 experiments, after which hydrse were imported by 

 scientific men as valuable curiosities. They were re- 

 discovered in England in 1743 by a Mr. Ducane, of 

 Essex. The important results consequent upon the 

 investigations undertaken at this time, have been 

 noticed in the introduction. 



