114 The Phenomena of Morphogenesis 



ferences in shape are often found between early and later fruits, or be- 

 tween leaves on different parts of the axis. Meijknecht (1955) has 

 analyzed some of these differences and concludes that this variation is 

 least when the structure occupies the position on the plant in which it 

 shows its "ideal" development, the expression of its typical specific charac- 

 ter. This calls to mind a concept of the early "idealistic" morphology. 



so 



40 

 3C- 



20 



-, /0 



So 



u 



- 8 



5 ' 



s 



Miniature' 



■1* 



x*.» 



'Giant' 



6 T 8 9 /o 

 Width (cm) 



40 SO 



Fig. 5-9. Relative growth of length to width in bottle gourds. Width increases faster 

 than length, but the relative rate is the same in "miniature" (dots) and "giant" 

 (crosses), so that although the shape of the two races at maturity is different, their 

 genotype for shape is the same. The inherited difference between them is in size. 

 (From Sinnott. ) 



The mechanism by which the control of relative growth is exercised 

 and growth correlation established is not known, but evidently cell 

 polarities are involved. Where growth is more rapid in one dimension 

 than in another, it has been shown (p. 51) that cell divisions are more 

 frequent in that direction. Whether the axis of the spindle or the cyto- 

 plasmic polarity by which this seems in certain cases to be preceded is 

 what is immediately involved in relative growth, or whether this is second- 



