,514 The Chromapliil Tissues and the Adrenal Medulla. 



extract made from the abdominal chromaphil bodies of three dogs. It will 

 be seen that the effect is identical with that of adrenin. In the same experi- 

 ment, a further injection of an extract made from the abdominal chromaphil 

 bodies of two dogs produced a comparable rise of blood-pressure. 



Mulon* has raised the blood-pressure of an animal by injection into the 

 circulation of an extract made from the carotid body of the horse. 



It seems clear, therefore, that all chromaphil tissues, wliether contained in 

 the adrenal or not, yield adrenin, or a substance having similar chemical 

 and pharmacodynamical properties. According to the views of the majority of 

 recent observers, the presence of this substance may be considered, in con- 

 junction with other observations, as evidence of an internal secretion on the 

 part of all these tissues. Kohn,f from morphological considerations, is 

 opposed to this view. He is certainly correct in insisting that because adrenin 

 has certain pharmacodynamic properties we have no right to assume, without 

 furtlier definite evidence, that it is one of the functions of the tissue to pour 

 out this substance into the blood-stream in order to produce beneficial effects 

 upon certain tissues of the body. He- considers that the cells forming the 

 medulla of the adrenal and chromaphil tissue elsewhere are not " epithelial," and 

 therefore cannot secrete. The present writer has replied to this argument 

 on a previous occasion,^ and a fuller discussion of the subject has recently 

 appeared.§ It must be admitted that the experimental evidence on the point 

 is contradictory, but there seems no reason why one cannot admit the hypo- 

 thesis that all the cliromaphil cells have an internal secretion, though this 

 process is more completely elaborated in the large chromaphil bodies, and 

 more especially in the adrenal medulla. 



The presence of a large strip of chromaphil tissue in the abdomen of the 

 dog and other animals, outside of the adrenals, is a very important con- 

 sideration in all extirjjation experiments, and the wide distribution of this 

 tissue in the body renders its complete removal impossible. 



EXPLANATION OF PLATE 13. 

 (Lettering common to all the figures.) 



bid. c, blood corpnsclea ; Idd. v., blood veasel.s ; n., capsule ; ehrmn. c, chromaphil cells ; 

 col. c, columnar cells of adrenal medulla ; conn, t., connective tissue ; end., endo- 

 thelium of blood vessels ; n., nuclei ; n.c, nerve cells ; n.f., nerve fibres ; v., vacuoles. 



* 'Arch. g6n. de MCd.,' 1!K)3, Ann6e 81, T. 2, No. 52. 



t Loc. ('it. 



X ' Anat. An/..,' 1!)00, Bd. 18. 



§ Vincent, ' Ergehnissc der Physiol.,' 1910. 



