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Note on a New Theory as to the Origin of Potato Tubers. 



By George Massee, F.L.S. 



{Read April Idth, 1901.) 



Until quite recently it was generally supposed that potato 

 tubers were included in the general scheme of evolution that 

 resulted in the production of the potato plant, their function 

 being that of reproducing the species in a vegetative or 

 asexual manner. In this supposition, from the point of view 

 of a Frenchman named Noel Bernard, we have been very much 

 mistaken. According to this gentleman, the presence of tubers 

 on a potato plant is quite accidental, and entirely depends on 

 irritation of the tips of the subterranean branches occasioned 

 by a minute fungus called Fusariuin Solani. It is comforting 

 to learn, however, that this particular fungus is so abundant in 

 the soil that it is practically impossible for potato stems to 

 escape the necessary irritation, which residts in a tuber. To 

 prove this theory the author planted sterilised potato tubers 

 in sterilised quartz sand. In some instances no tubers were 

 formed ; this proved the truth of the theory, so says M. Bernard. 

 In other cases a few tubers were formed, but according to the 

 author these were due to the fungus having gained access to 

 the roots in the sand. People genei'ally will require stronger 

 evidence before this romantic theory can be accepted. Many 

 people have planted potatoes under conditions much more favour- 

 able than that of sterilised quartz sand, and yet have failed 

 to secure a crop. Fusariuin Solani is considered by vegetable 

 pathologists as the fungus which causes one of the worst of 

 diseases to which potatoes are subject ; in fact, repeated experi- 

 ments have proved this opinion to be correct. 



