126 



THE AMERICAN NATURALIST [Vol. XL! 



Form Analysis. — Slowly but surely the necessity of applying pre- 

 cise mathematical methods to the solution of many biological prob- 

 lems is becoming apparent to workers in both fields. The chief 

 application of mathematical methods has been in the study of varia- 

 tion and heredity, but the problems of leaf form, arrangement of leaves 

 on the stem, and the convolutions of the shells of gastropods may be 

 mentioned as having attracted the attention of niath(Mnatical workers. 

 In an address before the American Phil()S()j)hi( a] Society, Michelson * 

 emphasizes the importance of the ])r(»l)lcni> >>\' syinnictry and suggests 

 a classification of symmetrical and uiisyuimctrical forms. 



J. A. Harris 



GEOLOGY 



River terraces at Brattleboro, Vt. Professor Fisher - Ims tesieil 

 the theory duit the river terraces of New England may he accounted 

 for by tiie behavior of meandering and swinging streams sh.wly 

 degrading previously aggraded vall.w> uiihout n.>cc.>an change in 



