THE ADIPOSE LOBE OP THE PELVIC PIN OP THE SALMON. 715 
conditiou. Beneath the membrane basale {M.b.) of the 
outer wall are numerous small pigment-cells [Pig.)'-, a few 
large isolated pigment-cells occur deep in the dorso-lateral 
surface. The connective tissue {G. t.) is more open in texture 
than that of the proximal region; the elongated nuclei of the 
cells [N.) are clearly depicted ; towards the surface the nuclei 
are fewer and rounder. The accessory scale in this region is 
typically triradiate in outline as appears in Text-fig. 2 (1), 
with a swelling where the rays meet; but it is sometimes 
compressed into masses, which are plate-like in section and 
much vacuolated. The succeeding sections sketched in Text- 
fig. 2 (2, 3) show that the scale is continued to the extreme 
distal end of the adipose lobe, though in the last, No. 4, it 
only consists of a. layer of scleroblasts {Schl.), by means of 
which growth is continued throughout life. 
(4) E X a, m in a ti o n of the Fat of the Adipose Lobe. 
Sections from all parts of the lobe, taken from fresh 
specimens or from those which have been preserv^ed in 
10 per cent, formalin or in Muller’s fluid, give the charac- 
teristic blackening on treatment with dilute osmicacid. This 
treatment is not entirely sati.sfactory, for while the fat-globnles 
tui-n black, the connective tissue is also affected to a certain 
degree, turning brown, and the fatty matter is not sufficiently 
clearly differentiated. A better result is obtained by ti’eating 
hand-sections, or frozen sections, with Sudan III according 
to the method described by Lee^ ; the fat-globules are then 
stained a deep oiange colour, while the other tissues are 
scarcely affected. The distribution of the fat in a section 
prepared in this manner is illustrated in fig. 5. Nearer the 
distal extremity the fat is almost entirely confined to the 
inner side of the acces.sory scale ; towards the base it spreads 
to the outer side, where it occurs in very considerable quan- 
tities. 
The fact that a stain is readily obtained with Sudan III at 
' ‘ Microtomist's Vade-Mecum,’ ed. vi, p. 376. 
