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THE AMERICAN NATURALIST [Vol. LIV 



This is a much closer approach to unity for the ratios than in 

 the case of facet values and the units employed may be taken as 

 fairly close measures of the temperature factor. 



A change of one facet is therefore not of equal factorial value 

 at different points on the variation scale as far as temperature is 

 concerned. A plotting of the data using facets as the units does 

 not give a uniform factorial scale. Suppose temperature to be 

 the only factor causing variation in the facet number of a par- 

 ticular stock but knowledge of the actual temperatures involved 

 in the production of a particular population to be lacking and it 

 is desired to derive the value of the temperatures from the facet 

 values. Obviously the closer approximation is obtained by the 

 tabulation in which each class has a facet range equal to a definite 

 per cent, of its facet mean. Krafka's data show that even in 

 this case the determination is not exact but certainly the error 

 is of a much lower order than that involved in using facets as 

 the units. 



Charles Zeleny 



AN EXPEKIMENT ON REGULATION IN PLANTS 1 



It is a fundamental faef Unit of the enormous number of buds 

 on a tree only a few of these normally develop into branches. 

 Every l)iul. however, has the capability of growth and will grow 

 into a branch if the more apical bud or buds are removed. Even 

 normally, in uninjured trees, some of the lateral buds grow into 



Child and Bellamy (Science, N. S., L, 362, 1919), in which somewhat 

 I'h.w,>!n:r!.-:il isolation of two regions of a whole plant was produced by 



