20 PLANARIA FLEXILIS. 



ways be renewed soon after the planariae 

 have fed, for an insensible putrescent prin- 

 ciple is imparted to it by their most salu- 

 tary aliment. On the water becoming fe- 

 tid, they rise to the surface, and endeavour 

 to escape ; thus pointing out an easy me- 

 thod of dislodging marine animals from their 

 recesses. By rendering sea-water noxious, 

 from the gradual decay of putrefying sub- 

 stances, they desert their haunts, other- 

 wise inaccessible, in quest of some more ge- 

 nial element ; or, if a tall glass jar be filled 

 with a promiscuous mixture of mud and 

 vegetables from a fresh water marsh, many 

 of its inhabitants will be seen ascending the 

 sides towards night, though, on the ap- 

 proach of day, they return to places of con- 

 cealment. 



The natural mode of propagation by the 

 Planaria Flexilis, seems from eggs : whe- 

 ther each animal is a hermaphrodite, I have 

 not been able to ascertain ; nor, indeed, all 

 the peculiarities attendant on the perpetua- 

 tion of their race. Some, which had been 



