52 HYDROZOA. 



rise to several others, in all respects similar to the 

 organism from which they were produced. These 

 for a time may remain in connection with each 

 other, but, more usually, they separate, each in its 

 turn, under favourable conditions, to repeat the 

 same budding process. The number of inde- 

 pendent beings into which a single Hydra, when 

 well supplied with food, and stimulated by a warm 

 temperature, may resolve itself, is certainly as- 

 tonishing. Not less so are its reparative powers, 

 which seem almost to defy the knife of the ana- 

 tomist. Full details on this subject are given by 

 Trembley, whose researches on the Hydra, pub- 

 lished in 1 744, are still well worthy of perusal. 



Some years ago, Ecker compared the periplastic 

 tissue of the Hydra to aggregate masses of the 

 sarcode, or " formless contractile substance," com- 

 posing the body of Amoeha. Mr. G-. H. Lewes 

 has also recognised distinct " contractile masses," 

 which he says were so very like Amoebae, as to 

 make him at first believe that the Hydra had 

 swallowed them. Such amoeboid particles occa- 

 sionally become detached by the method denomi- 

 nated *' diffluence," each usually including one or 

 more endoplasts ; but there is good reason to infer 

 that their apparently contractile movements are, 

 for the most part, the result of a process of en- 

 dosmose. Jager, however, has shown that two 

 budding Hydrae, each kept by him in a small 

 vessel of water, broke up into several isolated 

 particles, which, after the lapse of a month, were 

 still living, performed amoeba-like movements, 

 and, in some instances, passed into a peculiar 

 stage, resembling the encysted condition of Infit 

 soria. In this state, Jager supposes, they may 



