REFRODUCTION OF POLYPES. 299 



acquires the force of a law. I allude to it at starting, 

 because, inasmuch as the course of our inquiry will 

 conduct us to the conclusion that Generation is not 

 essentially a distinct process from that of Growth in 

 general, the idea of an ovum as the necessary origin of 

 every living thing needs to be modified. The first 

 illustration we owe to Trembley, whose Memoirs on 

 the Hydra, or Fresh-water Polype, are so admirable in 

 accuracy and extent of observation, that, in spite of 

 the labours of a century, nothing of what he stated 

 has been set aside, and very little added, except what 

 the microscope has revealed. He taught us that the 

 Polype, which originally comes from an Qgg, produces 

 a quantity of other Polypes, exactly similar to itself, 

 by a process of " budding," after the manner of a 

 plant. He taught us, moreover, that not only is this 

 the normal mode of multiplication, but that if we lace- 

 rate the Polype, each lacerated fragment will become a 

 new Polype, which in its turn may be cut into seve- 

 ral pieces, every one of them developing into perfect 

 Polypes. Several naturalists have repeated and con- 

 firmed his experiments. In repeating them myself I 

 failed at first, but subsequently succeeded, and attri- 

 bute the first failure to the presence of impurities in 

 the water containing the fragments. Mr E. Q. Couch 

 made the curious observation, * that if the body of the 

 Hydra " be merely irritated with a needle, or a ray of 



* Reports of the Penzance Natural History Society, 1850, p. 571. 

 SCHLEIDEN says of the Oesneria, that a puncture iu the leaf produces 

 a bud in a few days. The two cases are precisely similar. 



