714 



ADRIAN ZUMSTEIN UND PIERRE TARDENT 



SUMMARY 



1. The régulation of nematocyte-production following the sélective discharge of 

 stenotheles has been quantitatively and qualitatively investigated. 



2. As a first short-term reaction to sélective discharge difTerentiated stenotheles 

 which were already présent in the body-ectoderm move into the tentacles. 



3. In addition, the production (differentiation) of new stenotheles is increased 

 e.g. a larger number of stenothele-nematoblasts appear in the body-ectoderm. 



4. This increase of the nematoblast number is brought about by supplementaryi 

 mitotic divisions of the nematoblasts, preceeding nematocyst-differentiation. 



5. As a conséquence of the sélective discharge of stenotheles a larger number of 

 isorhizas and desmonemes moves into the tentacles, but it seems that this I 

 increased supply of thèse two types is not due to an obvious stimulation of] 

 their production at the level of differentiation. 



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