434 Ever-sporting Varieties 



termediate forms are very rare, perhaps wholly 

 wanting, though in swamps the terrestrial 

 plants may often vary widely in the direction of 

 the floating type. 



That both types sport into each other has 

 long been recognized in field-observations, and 

 has been the ground for the specific name of 

 amphibium, though in this respect herbarium- 

 material seems usually to be scant. The mat- 

 ter has recently been subjected to critical and 

 experimental studies by the Belgian botanist 

 Massart, who has shown that by transplanting 

 the forms into the alternate conditions, the 

 change may always be brought about arti- 

 ficially. If floating plants are established on 

 the shore they make ascending hairy stems, and 

 if the terrestrial shoots are submerged, their 

 buds grow into long and slack, aquatic stems. 

 Even in such experiments, intermediates are 

 rare, both types agreeing completely with the 

 corresponding models in the wild state. 



Among all the previously described cases of 

 horticultural plants and monstrosities there is 

 no clearer case of an ever-sporting variety than 

 this one of the water-persicaria. The var. 

 terrestris sports into the var. natans, and 

 as often as the changing life conditions may 

 require it. It is true that ordinary sports oc- 

 cur without our discerning the cause and with- 



