HYDRAS. 169 



both seize the same worm. In such cases the strong- 

 est wins, unless the worm breaks in the unfilial strug- 

 gle, when the parts go into the one common stomach, 

 through two separate mouths. Often two young 

 Hydras may be noticed growing from the sides of a 

 single older one, instances of which are shown in Fig. 

 130. The budded young finally separate from the pa- 

 rent, then leading an independent life, and soon pro- 

 ducing young Hydras from their own sides, if they have 

 not already done so. 



The creatures are very hardy. They will endure 

 much harsh treatment, and seem to thrive under it. 

 They have been made the victims of many apparently 

 cruel experiments," but they are probably not very 

 sensitive to a feeling of pain. The sensation of hunger, 

 and a sense of touch delicate enough to know when a 

 desirable morsel or an obnoxious object comes in con- 

 tact with the tentacles, are probably the extent of 

 their feelings. Trembley, a Dutch naturalist who 

 studied the Hydra as long ago as 1739, first called at- 

 tention to the harsh treatment they would endure and 

 live. In a rather quaint, old-fashioned translation it 

 is said that, "If one of them be cut in two, the fore 

 part, which contains the head and mouth and arms, 

 lengthens itself, creeps, and eats on the same day. 

 The tail part forms a head and mouth at the wounded 

 end, and shoots forth arms more or less speedily as 

 the heat is favorable. If the polype be cut the long 

 way through the head, stomach, and body, each part 

 is half a pipe, with half a head, half a mouth, and 

 some of the arms at one of its ends. The edges of 

 these half-pipes gradually round themselves and unite, 

 beginning at the tail end; the half-mouth and halfr 



