PLANARIA FELINA. 67 



tain nicety, of which I was not master, 

 should be practised : and that it had been 

 beyond my ability to detect the secret 

 cause of failure. 



But the powerful reproductive principle 

 which continually vegetates upwards, the 

 invariable acquisition of a head by the neck 

 from which it is severed, added to a similar 

 production in spontaneous division, gave 

 ground for conjecture, that if part only of 

 an incision healed, some generation still 

 upwards would ensue. On the other hand, 

 should the whole incision heal, matters 

 would remain entire. It was also most 

 likely, that the regenerating portion would 

 become a head, and that more than one 

 might thus be produced on the same ani- 

 mal. 



With this view, an incision, considerably 

 lower than the head, was made in three 

 planariae, on the twenty-eighth of Sep- 

 tember. It completely healed in two, and 

 the animals appeared almost as if untouch- 

 ed. One of them survived above a year, 



