PHYSIOLOGICAL (OR CONSTITUTIONAL) UNITS. 617 



Canon Ellacombe that some of the Berlin Hellebores show evidence of their 

 hybrid nature by occasionally producing foliage [and flowers ?] of the two 

 parents separately from the same root-stock. 



" In addition to the cases given above, we may here cite a few more which 

 have come under our notice, such as a Chrysanthemum, half the florets of 

 which are of one colour, half of another. A hybrid Calanthe, showing a 

 similar piebald variation, is shown in Fig. 14. A very curious case was that 

 of the Narcissus received from Mr. Walker, and in which flowers of two 

 distinct varieties sprang from the same bulb. Grapes not uncommonly 

 show their crossed origin by presenting a striped appearance, one stripe 

 being of one colour, one of another, as may also be seen in the Orange, 

 Apple, Lemon, and Currant." 



Thus, however the germ-plasm is constituted its essential com- 

 ponents cannot be all alike. Before there can be this dissociation 

 of ancestral characters, there must be in the germ-plasm different 

 elements capable of being dissociated. This single fact seems to 

 compel us to assume constitutional units. 



