FIELDS AND GRADIENTS 



275 



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fer 

 li 



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I 







p 



f 





Fig. 130 



Differential susceptibility in the primitive oligochaete Aeolosoma. Above, four 

 stages in the disintegration of a worm with a well-developed posterior zooid 

 nearly ready for detachment, exposed to Nj 100 KCN. Below, graph of the axial 

 gradient of a similar specimen. The abscissae represent the ordinal number of 

 the segments, the ordinate the time to death in the toxic solution, in minutes. 

 (From Hyman, Jourw. Exp. Zool. xx, 1916.) 



18-2 



