THE FLORAL WORLD AND GARDEN GUIDE. 



fact brings us back to the classics, and, we may say, that Hydra ia 

 like Achilles in this respect, that he is invulnerable everywhere, 

 except in the heel. I have suc- 

 ceeded in removing a single ten- 

 tacle, which soon became a com- 

 . plete animal, and I have cut off 

 the heads of two and made them 

 change heads, which they did 

 with gladness, or, at all events, 

 without a token of discontent. 

 To turn one inside out is an old 

 trick difficult to perform. AVhen 

 it is accomplished, the creature 

 appears none the wors^e, but feeds 

 freely and digests its food as 

 before. I have seen one thrust 

 inside another and the two united 

 and become one. I quite ex- 

 pected the outer one would di- 

 gest the inner, but they appeared 

 to understand each other, and 

 instead of the swallowed animal 

 becoming a mere victim, it became 

 a partner in the business. 



The usual manner, however, 

 in which it multiplies its species 

 appears to be by gemmation, that 

 is, it has the power of sending 

 forth, from different parts of its 

 body, a little bud or gemma, 

 which at first has the appearance 

 of a shapeless excrescence, which 

 in a short time becomes de- 

 veloped into a body similar to 

 its parent, having arms, a mouth, 

 and stomach. Until, however, 

 it is fully formed and perfected 

 in all its parts, it remains at- 

 tached to its parent by a short 

 pedicel, and enjoys, by this 

 means, an entire communication 

 of food, by that of one freely 

 pasj^ing into the other. Some- 

 times this offsprout puts out another bud, even while it is 

 attached to its parent, so that three generations may be united 

 together. Trembley even found that by snipping the side of an 

 adult polyp with the points of a fine pair of scissors, that a bud was 

 soon developed from the wounded part, and that by making this 

 experiment repeatedly, both upon the parent and its progeny, lie]ob- 

 tained as many as seventeen all connected with each other. 



End of Arm (tentacu)e), liigliiy maguJ- 

 fied. — a, investing membrane ; b, 

 ■wart- like knobs ; c, prehensile darts ; 

 d, organs of touch ; e, longitudinal, 

 and J] transverse, muscular bands. 

 (After Corda.) 



October. 



20 



