ADRENALIN IN ANNELIDS. 



A Contribution to the Comparative Study of the Origin of 



THE Sympathetic and the Adrenalin-Secreting Systems 



AND OF the Vascular Muscles Which They 



Regulate. 



By J. F. GASKELL. 



(From the Laboratory of Pathology, St. Bartholomew's Hospital, and the Physiolog- 

 ical Laboratory, Cambridge, England.) 



(Received for publication, July 16, 1919.) 



The intimate physiological relationship between the sympathetic 

 nervous system and the adrenalin-secreting cells of the medulla of 

 the suprarenal body is now thoroughly established. All the actions 

 of the sympathetic system can be imitated by adrenalin, and failure 

 of the adrenalin supply, such as takes place in Addison's disease, 

 causes failure of the proper action of the sympathetic nerves. The 

 morphological relationship of the two types of cell, the sympathetic 

 nerve cell and the adrenalin-secreting cell, are also equally intimate. 

 The adrenalin-secreting cell is always identifiable in mammals by its 

 chrome-staining reaction. Elhott^ has brought forward strong evi- 

 dence that the innervation of the medullary cells of the suprarenal 

 body is a direct one by the medullated connector or tract fibers of the 

 splanchnic nerves. Such an innervation corresponds to the white rami 

 communicantes which connect with the sympathetic nerve cells in 

 their various gangha. 



In the higher mammals the sympathetic ganglia do not usually con- 

 tain any adrenalin-secreting cells, the latter being concentrated 

 almost entirely in the special tissue of the suprarenal medulla; but 

 in the lower forms of vertebrates the two tissues are both widely dis- 

 tributed and intimately connected. In amphibia, for instance, islets of 

 chrome-staining tissues are to be found in every sympathetic ganglion, 



1 Elliott, T. R., J. Physiol, 1913, xlvi, 285. 



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