898 



FRANZISKA BRIEGEL-HANIMANN 



amount of ninhydrin-positive substances decreases during gastrulation and 

 increases thereafter untill after hatching. This increase coincides with the break- 

 down of yolk and cellular differentiation during neurulation and larval develop- 

 ment. The quantitative changes of individual amino acids and derivatives appear 

 to be stage-specific and are partly correlated with those of the total amount. 



6. The biochemical and morphogenetic significance of the présent results 

 for the embryonic development of amphibians is discussed. 



F. LITERATURVERZEICHNIS 



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