718 
EDWAED A^■. SHANN. 
but tlarkei' iu colour. This condition obtained till the nine- 
teenth day, ■when the blue became more scarce again, indi- 
cating the approach of saturation. On the twentieth day, 
after -which the observations were discontinued, the blue had 
almost disappeared. 
A parallel series of observations was made with sections 
from the adipose dorsal fin of the same fish. In this case a 
distinct blue coloration was produced on the first day of 
bicliromating, showing that oxidation had begun. Tiie blue 
specks increased in number and in intensity of colour till the 
third day. The condition remained practically constant until 
the sixteenth day, when the colour became less intense and 
the specks fewer, indicating the approach of saturation. The 
fading continued until the twentieth, and last, day of the 
investigation. 
While admitting that the foreg’oing experiments throw very 
little light, in the absence of other data, upon the chemical 
affinities of the fats under examination, they are highly 
relevant as emphasising’ the qualitative difference between 
them. We see, firstly, that the deposit in the adipose dorsal 
fin becomes oxidised much more readily than does that in the 
adipose lobe of the ventral fin ; secondly, that the saturation 
point is approached at a correspondingly earlier date in the 
former than in the latter. We may, therefore, conclude that 
the fat in the lobe is of a more stable nature than that in the 
adipose dorsal fin. 
III. The Development oe the Adipose Lobe. 
For the purpose of examining the details of tlie development 
of the adipose lobe I was fortunate enough to obtain a very 
complete series of 3mung salmon, which were all hatched on 
the same day, and were removed from the water at intervals 
of a few weeks. The following table will show the age, size, 
and external appearance of the lobe in the eleven specimens 
which are to receive notice in this section : 
