170 VITALISM AND SCHOLASTICISM 



Tubularia 



Planaria 



shore can scarcely have failed to have seen 

 specimens of the creature called Tubularia. 

 It has a stem, the base of which is embedded 

 in the sand and a head-end surrounded by a 

 ring of tentacles and provided with a sort of 

 proboscis. Almost anything can be done with 

 this creature in the way of regeneration. If 

 the head be snipped off the base will grow 

 a new head and the head a new base, just as 

 a worm chopped in two will do. If instead 

 of cutting it the animal be pulled up by the 

 roots and replanted head downwards the head- 

 end develops roots and the root-end becomes 

 a head with tentacles and proboscis. 



Finally, if we snip off the head and tail of 

 the polyp and hang it up horizontally in the 

 water by a thread, it will grow a head from 

 either end. 



Another creature Planaria, a parasitic worm, 

 can be cut up into a number of pieces all of 

 which will develop into complete individuals. 

 Moreover like the Hydra it can be partially 

 bisected and will then grow into a kind of 

 two-headed Nightingale amongst Planarians, 

 with a single body and two heads. More 

 wonderful still if oblique cuts be made into the 

 sides of the body new heads or tails will grow 

 from them according to the direction in which 

 the incisions have been made (fig. iv.). 



