SUPRARENAL GLAND—EFFECTS OF INANITION 269 
the cortical anlage and finally collect in the center of the gland. 
Here they later become confluent, a few cells (‘sympathoblasts’) 
forming the sympathetic ganglion cells, the majority ‘phiochro- 
moblasts’ or ‘chromaffinoblasts’) ripening into the characteristic 
parenchyma of the medulla. 
The time at which this confluence of the medulla is finally 
completed varies in different mammals, but is usually during the 
late fetal period. In Echidna, however, the immigration of the 
sympatho-chromaffin anlage is greatly delayed, and the supra- 
renal medulla is not formed until long after birth (Keibel, ’04). 
Also in the new-born mouse (Inaba, ’91), cat, dog, and guinea-pig 
(Soulié, 703) and occasionally even in the human new-born 
(Starkel and Wegrzynowski, ’10; Zuckerlandl, ’12), the process is 
still incomplete and admixture of cortex and medulla persists to 
a variable extent after birth. In the mouse, Inaba (’91) found 
the corticomedullary boundary line still indefinite at ten days, 
but distinct at thirty days. 
Soulié (’03) described the confluence of the medulla in the 
suprarenal of the rat (Mus decumanus) as appearing in the 25-mm. 
fetus. Dewitzky (’12), however, found the suprarenal medulla in 
the rat very ill defined at birth, becoming distinct at three days 
and thereafter. This is in general agreement with my observa- 
tions, although I find the confluence of the medulla in the albino 
rat to be a gradual process and subject to some individual varia- 
tion. Itis usually completed by the end of the first week. Even 
in the adult, however, short cords of cortical tissue may occa- 
sionally extend into the medulla, as observed by Bonnamour 
(05 a) in the rat and rabbit, and small cortical islands occur 
near the margin of the medulla. 
As to the exact manner in which the confluence occurs, but 
few definite statements appear in the literature. Flint (00) 
mentions.appearances of pressure atrophy in the cortical strands 
in the medulla of the suprarenal in the fetal pig, and Soulié (’03) 
states that the cells of the medulla anlage ‘‘etouffent peu a peu 
les cordons corticaux emprisonnés au stade de pénétration.”’ It 
seems to be generally assumed, however, as is stated definitely 
by Inaba (’91) for the mouse, that these cortical cell strands and 
