ON SUPRAKEXAL BODIES IN THE MOUSE. 



229 



they can not be traced to tlie ganglion, but are lost on the way ; iti 

 otliers again, they are lost in the connective tissue capsule of the organ. 

 rro7n this stage onward we can call the nervons elements within tlie 

 suprai-enal more appr(^i)riately the medulla. I l)elieve this and tlie 

 previ(Mis stage are snfticient to show the nature of the medullary 

 substance. Probal)ly these two stages were not observed by 

 (rottscliau and Janosik. who thus concluded that the medulla is 

 differentiated gradually from the cortical substance. 



Woodcut 9. 



Cross soction takon from a Itltli day embryo, rif^lit side suprarenal, 



A, at the mid<llo of the or^-au. P.. near the posterior end. 



c. v. = central vein. oor. = cortex, med. = medulla, sy. "•. = o-ano'lion of sympathetic 



origin. 2xBB. 



As to the further growth of the medulla, I have little to describe. 

 It consists merely in the increase oi' the medullary cells which 

 gradually form a compact mass in the centre of the organ, the cortical 

 substance becoming in consequence scanty in the centre and pushed 

 to the; ])eriphery. (PI. XXXI. 14) 



The severance of the nervous connection commenced in the 

 previous stage is usually complete in the 18th day embryo, which 



