PLANARIA FLEXILIS. 11 



Plaiiariae, like most marine animals, de- 

 sert their haunts at night, and range ac- 

 tively around in quest of prey. An incre- 

 dible change is produced in their appear- 

 ance by the immoderate quantities they 

 devour, insomuch that they can scarce be 

 recognized for the same beings. 



I was particularly unsuccessftd in endea- 

 vouring to discover the proper food of the 

 planaria ilexilis ; every different substance 

 was rejected ; and, in the interval thus oc- 

 cupied, all the animals successively procu- 

 red gradually wasted away to extenuation. 

 It occasioned me the greater regret, from 

 their rarity in the districts within my reach ; 

 and experience had taught me, that the 

 most essential condition which can aid in- 

 vestigations into the phenomena of ani- 

 mated nature, is ascertaining the aliment 

 whereby life is preserved. A new oppor- 

 tunity having occurred on the 31. of Au- 

 gust 1809, three planariae, after an absti- 

 nence of several days, were supphed with 



the heart and liver of a perch ; the sea wa- 

 1 



