200 The Phenomena of Morphogenesis 



cells and others, and thus inhibits differentiation of stomata (and some- 

 times of hairs or glands). Near wounds, cell division occurs but stomata 

 are not differentiated. If auxin paste or juice from crushed tissue, pre- 

 sumably containing wound hormones (p. 402), is applied to the young 



Fig. 8-12. Relation of nuclei to stomata. Nuclei of cells adjacent to stomatal initials, 

 in young and developing leaves, are pressed closely to these initials as if chemically 

 attracted to them. ( From Biinning and Sagromsky. ) 



leaf, cell divisions are plentiful but stomata do not develop (Fig. 8-13). 

 This suggestion is of much interest in relation to the differentiation of 

 other evenly spaced structures, but it does not explain how the inhibiting 

 center itself is initiated in the first place. This is a promising point, how- 

 ever, at which to attack the problem of organic pattern. 



In the histological pattern that originates back of the apical meristem, 

 Biinning ( 1952# ) believes that the meristem itself inhibits differentiation 

 within a certain distance. Farther back, each bundle initial, which is in the 



Fig. 8-13. Left, epidermis of developing leaf two weeks after treatment with auxin 

 paste. Stomata are almost absent. Right, epidermis of untreated half of the same 

 leaf. ( From Biinning and Sagromsky. ) 



