404 SEA-SIDE STUDIES. 



presented to Mm. The fact is demonstrable, that both 

 Contractility and Sensibility are manifested by animals 

 totally destitute of either muscles or nerves. Some 

 physiologists, indeed, misled by the a priori tendency 

 to " construct " the organism in lieu of observing it, 

 speak of the muscles and nerves of the simplest animals ; 

 because, when they see the phenomena of Contractility 

 and Sensibility, they are unable to dispossess themselves 

 of the idea that these must be due to muscles and 

 nerves. Thus, when the fresh-water Polype is seen 

 capturing, struggling with, and finally swallowing a 

 worm, yet refusing to swallow a bit of thread, we can- 

 not deny that it manifests both Sensibility and Con- 

 tractility, imless we deny these properties to all other 

 animals. Nevertheless, the highest powers of the best 

 microscope fail to detect the slightest trace of either 

 muscle or nerve in the Polype. Leydig, indeed, de- 

 scribes and figures what he calls the muscles of the 

 Hydra.'^ But what are they ? A network of contrac- 

 tile cells of irregular shape, such as Ecker -|- had pre- 

 viously described as the " unformed contractile sub- 

 stance," with this difference, that Leydig discovers a 

 nucleus attached to the wall of each cell. I have 

 seen it often, but the observation by no means war- 

 rants the conclusion that this proof of the network 

 being cellular, is a proof of its being muscular. The 

 cells resemble muscles in no respect, except that 



* Op. cit. 



+ EcKER, Zur Lehre vom Baic imd Lehen der contradilen. Substam 

 der niedersteii Thiere. 



