author's abstract of this paper issued 

 by the bibliographic service, june 27 



DIRECT DEMONSTRATION OF THE EXISTENCE OF 

 A METABOLIC GRADIENT IN ANNELIDS 



LIBBIE H. HYMAN AND ALBERT E. GALIGHER 



Hull Zoological Laboratory, University of Chicago 



THREE FIGURES 



INTRODUCTION 



For a number of years evidence has been presented from this 

 laboratory concerning the existence of metaboUc gradients in 

 organisms. This evidence has been obtained through the use 

 of several methods. These may be summarized briefly as 

 follows : ^ 



1. Regeneration method. In pieces cut from different levels 

 of the axis of simple organisms the rate of regeneration and the 

 kind of structure regenerated exhibit graded differences corre- 

 lated with the level from which the pieces are taken. These 

 differences in the regenerative phenomena at different levels 

 cannot be due primarily to morphological factors, but are func- 

 tional in nature, since they depend upon the size of the piece 

 and are easily alterable by conditions whose action is chiefly 

 quantitative. 



2. Direct susceptibility method. Different levels of the axis 

 of simple organisms exhibit a differential susceptibility to con- 

 centrations of toxic substances which will kill within a few 

 hours. Since the death gradients of organisms in such solutions 

 are the same for a large variety of toxic substances of widely 

 different chemical constitution, these gradients cannot be due 

 solely to the specific mode of action of these substances, but 

 must depend rather upon a general quantitative gradation of 

 some sort existing within the organism itself. The suscepti- 



1 For a more complete discussion of these methods together with references 

 consult Child ('20). 



1 



