WEISMANN'S THEORY OF THE GERMPLASM 51 



pathological conditions, retains the power of pro- 

 ducing roots. Beyerinck has shown that galls of 

 Salix purpurea, planted in moist earth, bear 

 rootlets identical with those of the normal plant. 

 As the roots of all woody plants are able to bear 

 adventitious buds, De Vries thinks it probable that 

 one could rear a whole willow-tree from a gall. 

 That would imply that all the inheritable characters 

 of the willow were contained even in the gall. 



Loeb has produced heteromorphoses experi- 

 mentally upon many lower animals, among which 

 were Tubularla, Cerianthus, and Clone intesti- 

 nalis. 



In Tubularia mesembryanthemum, a hydroid 

 polyp, there are stalk, root, and polyp-head. If 

 one cut off the head, a new head will be formed in 

 a few days, this being a case of regeneration. On the 

 other hand, a heteromorphosis may be produced by 

 modifying the experiment as follows : Both root 

 and head must be cut from the stem ; if the lopped 

 piece of the stem be stuck in the sand of the 

 aquarium by the end that bore the head, then the 

 original aboral pole in a few days produces a head ; 

 if the lopped piece of stem be supported hori- 

 zontally in the water, then each end of it produces 

 a head. 



In a Cerianthus membranaceus (Fig. 1), the 

 body was opened by a cut some distance below the 

 mouth, whereupon buds appeared on the lower 

 edge of the slit, where the experimenter had pre- 

 vented coalescent growth. These buds gave rise 

 to inner and outer tentacles, and an oral disc was 



