PLANARIA NIGRA. 27 



to the number of eyes, or their total ab- 

 sence ; and a place from the latter was as- 

 signed to the black planaria. It was pro- 

 bable, liowever, if eyes were present, they 

 should not be sought in the full grown ani- 

 mal, which might be of equal opacity to 

 themselves ; or, in other words, they would 

 more easily be detected in regenerating 

 parts : and, if such lacerations as I had wit- 

 nessed did not destroy the animals, nei- 

 ther would artificial separation of important 

 organs be fatal. Several planariae were 

 therefore decapitated on the tenth of Sep- 

 tember ; and, in nearly three weeks, the 

 wounds of some being examined by a mag- 

 nifier, appeared not only completely heal, 

 but a conical reproduction of the defective 

 parts protruded. The regenerated organs 

 of all animals are light and colourless ; and 

 I thought that a row of minute marginal 

 specks, such as are usually called eyes in 

 the vermes and molluscae, was discernible. 

 This proved no illusion, for, on the twenty- 

 ninth of the month, they were distinctly 



