R. H. Whitehead 359 
distinct ganglion may appear in another as an integral part of the man- 
tle. The anatomical similarity of the cells composing the mantle, the 
connecting strands, and the ganglia is so great that it is exceedingly 
difficult to draw any distinctions between them (Fig. 6). One easily 
gets the impression that strands of cells from the ganglia enter the 
adrenal along its dorso-medial aspect, and, growing along the lines of 
least resistance, spread out beneath the capsule and send in prolonga- 
tions between the cortical rows. The continuity between the mantle 
and the sympathetic ganglia, and the identity in appearance of the cells 
composing them seem to offer anatomical evidence quite positive in 
character. 
--—-Med. 
Fic. 6. Pig 35 mm. Section 5 mikrons thick. Leitz obj. 7, oc. 4. S.g., portions 
of sympathetic ganglia; Man., mantle layer of cells; (Cc., portions of cortical 
columns; Med., collections of medullary cells. 
Two objections to this view present themselves: May not the mantle 
cells be derived from the periphery of the cortex? My preparations 
afford no foundation for this hypothesis. There is no evidence that 
karyokinesis is more abundant at the periphery than elsewhere in the 
cortex, and there is entire absence of transition forms between the corti- 
cal cells and those of the mantle. Again, granting that the mantle cells 
are derived from the sympathetic ganglia, may they not subsequently 
perish in great part, as has been shown to be the case with many neuro- 
blasts in the substantia gelatinosa of the spinal cord, and as Minot thinks 
probably occurs in the human adrenal? I think the work of Flint, 
many of whose preparations he has kindly allowed me to examine, fur- 
