IIYDKAIDiE : HYDRA. 135 



develops a new animal, whicli is itself capable of being multiplied 

 in the same extraordinary manner. If the section is made length- 

 ways, so as to divide the body into two or more slips connected 

 merely by the tail, they are speedily resoldered, like some heroes of 

 fairy tale, into one perfect whole ; or if the pieces are kept asunder, 

 each will become a polype ; and thus we may have two or several 

 polypes with only one tail between them ; but if the sections be 

 made in the contrary direction — from the tail towards the tenta- 

 cula — you produce a monster with two or more bodies and one 

 head. If the tentacula — the organs by which they take their prey, 

 and on which their existence might seem to depend — are cut away, 

 they are reproduced, and the lopt-ofF parts remain not long without 

 a new body. If only two or three tentacula are embraced in the 

 section, the result is the same ; and a single tentaculum will serve 

 for the evolution of a complete creature.* When a piece is cut out of 

 the body, the wound speedily heals, and, as if excited by the stimulus 

 of the knife, young polypes sprout from the wound more abundantly, 

 and in preference to unscarred parts ; when a polype is introduced 

 by the tail into another's body, the two unite and form one indi- 

 vidual ; and when a head is lopt off, it may safely be ingrafted on 

 the body of any other which may chance to want one. You may 

 slit the animal up, and lay it out flat like a membrane, with im- 

 punity : nay, it may be turned inside out, so that the stomachal 

 surface shall become the epidermous, and yet continue to live and 

 enjoy itself.t And the creature even suffers very little by these 



haclie. Ces petits morceaux de peau, tant ceux qui avoient des bras, que ceux qui 

 ii'en avoient point, sont devenus des polypes parfaits." Trembley, Mem. 248. — 

 Rome de Lisle attempted to lessen the remarkableness and singularity of this fact by 

 supposing that the Hydra was a colony of minute animalcules held together in a 

 moveable polypidom, represented by the thin outer cuticle, and of course that this 

 cutting and division only set free a number of independent entire beings. The 

 hypothesis is a bold one, but has nothing in the way of observation to support it. — 

 See Blainv. Actinol. p. 563. 



* From the experiments of Trembley (Mem. 235), of a correspondent of Baker's, 

 and of Baker himself, it would seem that a tentaculum cannot produce a new body 

 unless a part of the head or body is removed with it (Hist. 193-4) ; but other ex- 

 perimentalists are said to have succeeded when this was done. For the particulars 

 stated in the text, and others equally incrediljle, the reader may consult the works of 

 Trembley and Baker, passim. 



t Trembley had several by him " that have remained turned in this manner ; their 

 inside is become their outside, and their outside their inside : they eat, they grow, 

 and they multiply, as if they had never been turned." — Phil. Trans. Abridg. viii. 

 627 ; and his Mem. 253, &c. 



