OAKUßN- 



Growth and variation in maize '\ 



By Raymond Pearl aud Frank M. Surface. 



(Eingegangen 6. April 1914). 



UlHKARt 



The iuvestigatiou reported iu this paper is au attempt to analyze "^^^ ^ 

 normal „fluctuating" variation in a particular case, from the standpoint * 

 of Entwicklungsmechanik. It is a direct outgrowth from, and 

 indeed in some respects, a supplement to a study of variation and 

 differentiation in Ceratophyllum made some years ago by one of the 

 present writers (Pearl, '07), We have here attempted to approach 

 the problem of inter-individual variation from the same point of view 

 and with similar methods to those applied to the problem of in tra- 

 in dividual variation in the case of Ceratophyllum. 



Our problem and our point of view may be most clearly defined 

 by considering briefly certain well-known, indeed obvious, facts about 

 variation. If one brings together a homogeneous group of individual 

 plants or animals and measures the same character in each individual, 

 there may be formed from the resulting data a characteristic variation 

 curve for that group and character. The precise form of this curve, as 

 well as the location in it of any particular individual, are functions of 

 two basic variables. Of these one is the hereditary or germinal con- 

 stitution of the individual. The other is the complex of environmental 

 stresses and strains, which, each acting on the individual at some time 

 during its ontogeny, have influenced the end result of the activity of 

 the hereditary determiners or genes. 



Now it is altogether usual in discussion of variation and heredity 

 to take the two end terms of the ontogenetic series, the gene on the 



^) Papers from the Biological Laboratory of the Maine Agricultural Experiment 

 Station, No. 64. 



Induktive ÄbstammungB- und Vererbungslehre. XIV. 7 



