654 Mutations 



assuming the features of their presumable an- 

 cestors. In his work on the survival of the un- 

 like, Bailey has given a detailed description of 

 these various types. Moreover, he has closely 

 studied the causes of the changes, and shown 

 the great tendency of the tomatoes to viciriism. 

 By far the larger part of the observed cases of 

 running out of varieties are caused by acciden- 

 tal crosses through the agency of insects. Even 

 improvements are not rarely due to this cause. 

 Besides these common and often unavoidable 

 changes, others of greater importance occur 

 from time to time. Two of them deserve to be 

 mentioned. They are called the *' Upright " and 

 the *' Mikado " types, and differ as much or 

 even more from their parents than the latter do 

 from any one of their wild congeners. Their 

 characters come true from seed. The ^' Mika- 

 do " race or the Lycopersicum grandifolium (L. 

 latifolium) has larger and fewer leaflets than 

 the slender and somewhat flimsy foliage of the 

 common form. Flat or plane blades with de- 

 current margins constitute another character. 

 This variety, however, does not concern our 

 present discussion. The upright type has stiff 

 and self-sustaining stems and branches, resem- 

 bling rather a potato-plant than a tomato. 

 Hence the name Lycopersicum solanopsis or L. 

 validum, under which it is usually described. 



