DEVELOPMENT OF THE ADRENALS IN THE TURTLE 73 



Although the theory that the suprarenals, or the chromaffin 

 substance, are derived from the sympathetic nervous system was 

 so well supported by the work of these early investigators, later 

 observers have repeatedly failed to recognize the nervous origin 

 of these bodies and have attempted to derive them from some 

 other source. This condition is probably due in part to a failure 

 to recognize the homology of the chromaffin substance of the 

 adrenals of the higher vertebrates with the suprarenals of the 

 fishes and in part to an erroneous interpretation of observations 

 coupled with an unwillingness to believe that any part of the 

 adrenals is derived from the sympathetic nervous system. 



Gottschau ('83), working with mammalian embryos, noted the 

 intimate association of the chromaffin substance with the corti- 

 cal substance and concluded that both arise from the mesenchyme. 

 Janosik ('83) observed that in mammalian embryos cells advance 

 from the peritoneal epithelium into the mesenchyme in the region 

 in which the adrenals arise. He concluded, therefore, that these 

 bodies are derived from the germinal epithelium. Like Gottschau 

 he believed that the cortical and the chromaffin substance are 

 derived from the same source. O Schultze ('97) concluded, from 

 observations made on embryos of Vespertillio murinus, that the 

 entire adrenal anlage is derived from sympathetic ganglia and 

 that it is later differentiated into a cortical and a medullary 

 portion. Minot ('97) found no evidence of the sympathetic 

 origin of any part of the adrenals in human embryos, but sup- 

 ported the older view of Gottschau that both the cortical and the 

 chromaffin substance are derived from the mesenchyme. 



The above citations are sufficient to indicate that there has 

 been no general agreement in the conclusions to which the earlier 

 investigators were led. A similar lack of agreement, though less 

 marked, is also prevalent among the later investigators. 



Flint ('00), in his paper on the blood vessels of the adrenals, 

 does not attempt to determine the ultimate source of either the 

 cortical or the chromaffin substance. He shows, however, that 

 in embryos of the pig the cortical substance arises first and that 

 the chromaffin substance arises from cells which wander in from 

 the outside. That the cells which give rise to the chromaffin 



