58 PLANARIA FELINA. 



delicacy in separating the component parts, 

 and the nicest observation in other cases, 

 have detected those rudiments of organiza- 

 tion, which are wont to be exposed only in 

 the perfect state. Here the like evolution 

 succeeds ; but the experiment seems be- 

 yond human ability. Microscopical obser- 

 vation discovers nothing more in the sepa- 

 rated fragments, than what unassisted vi- 

 sion has seen. There is no indication of 

 specks or tentacula: no symptom of an 

 aperture for the protrusion of the future 

 proboscis. The anterior not being reduced 

 to an edge, remains of considerable thick- 

 ness ; it is smooth, even, and resembles a 

 piece of flesh divided by a sharp knife. 



It has before been explained, that all ani- 

 mal reproductions being materially influen- 

 ced by the heat of the atmosphere, the re- 

 newal of defective parts is accelerated or 

 retarded accordingly. Some fragments, 

 therefore, are perfected earlier than others ; 

 but increment advances even where the 

 temperature is low. It would be interest- 



