246 Cc. M. JACKSON 
philic, with a bluish-violet stain, in contrast with the typical 
reddish (eosinophile) color in the cytoplasm of the cortical cells. 
The nuclei appear similar to those of the adjacent cortex. ‘The 
stroma is not clearly differentiated. The deeply staining cell 
clusters above referred to are apparently in most cases remnants 
of the embryonic sympatho-chromaffin cells, consisting of 
deeply staining nuclei with scanty cytoplasm. They are dis- 
tinct from the intermingled cortical cell strands, which are 
especially evident in preparations stained for lipoids or .chro- 
maffin reaction. 
The chromaffin reaction is present, but faint, in the new-born 
rat and increases but slightly in intensity during the first week. 
The medulla cells assume a pale brownish color, by which they 
may be clearly distinguished from the cortex and from the in- 
termingled cortical cord present in the medulla. In mammals 
generally the chromaffin reaction of the medullary cells appears 
during the fetal period (compare Poll, ’05) and was noted by 
Soulié (’03) well marked in the new-born rat and guinea-pig. 
Lipoids. In unstained frozen sections of the suprarenal (for- 
malin-fixed a few hours) in the new-born rat, the cortex appears 
opaque, due to the emulsion formed by the lipoidal granules. 
Following the terminology of Albrecht and Bell, these lipoidal 
granules and droplets will be designated as ‘liposomes.’ They 
are soluble in absolute alcohol and xylol, but insoluble in 1 per 
cent aqueous potassium hydroxide and in 1 per cent acetic 
acid. With the exception of an indistinct clear streak between 
the outer and middle zones, they appear somewhat uniformly 
distributed throughout the cortex and in the cortical cell strands 
extending throughout the medulla. 
These sections, when stained with Herxheimer’s scarlet red 
or with 1 per cent osmic acid and mounted in glycerin, reveal 
still more clearly the liposomes (fig. 1). Although not so abun- 
dant as later, the lipoids appear in much larger amount than 
would be expected from the corresponding lipoidal vacuoles 
as seen in the usual stained paraffin sections. Their staining 
reactions already appear distinct from those of the ordinary 
fat droplets outside of the fibrous capsule, even when these 
