PHYSIOLOGICAL CHARACTERISTICS OF AXIATE PATTERNS i6i 



any marked outgrowth the hmb buds are regions of rapid reduction with 

 decrease in rate more or less radially from a center, as in buds generally. 

 In these embryos the rapid reduction in the region of the heart and gills 



Fig. 55, A~J. — Differential reduction of Janus green in later stages of chick embryo. 

 A-C, four-somite stage with injury and retardation or absence of reduction in neural folds; 

 D-F, twelve-somite stage; G-I, twenty-somite stage; /, early limb-bud stage(from Rulon, 1935). 



may be in part due to more rapid decrease of oxygen there in consequence 

 of the crowding of parts. In still later stages each feather germ stands 

 out as a region of more rapid reduction than the skin about it. 



