ORGANIC CONSTITUENTS OF THE SCALES OF FISH. 
101 
SUMMARY. 
The above experiments show that in the scales of the teleosts ichthylepidin is 
widely distributed; in the scales of elasmobranchs and of Mola viola and Spheroides 
maculatus it is absent. The species cited by Morner in his paper as having ichthy- 
lepidin in their scales are here given: 
1. Abramis brama. 
2. A spins rapax. 
3. Carassius vulgaris. 
4. Clupea harengus. 
5. Coregonus lavaretus. 
6. Esox Indus. 
7. Leudscus idus. 
8. Leudscus rutilus. 
9. Lucioperca sandra. 
10. Perea fluviatilis. 
11. Salmo salar. 
12. Sebastes marinus. 
In the ganoid scales of the gar-pike (Lepisosteus osseus) lie found no ichthylepidin. 
Our experiments, however, show that it is detected by Morner’s reactions in the 
scales of the sturgeon (Acipenser sturio). 
The scales of the sun-fish have the same general chemical composition as those 
of the elasmobranchs, and quite different from the scales of other higher fishes. 
PROPORTION OF COLLOGEN AND ICHTHYLEPIDIN. 
Morner found the relative amounts of collogen and ichthylepidin in the organic 
matter of the scales of four species of fish to be, approximately, 1 parts of the former 
to 1 part of the latter. The determinations were made indirectly by estimation of 
the total sulphur. In two cases we have found the relative amounts directly by 
separation of the ichthylepidin and weighing it, the collogen being calculated from 
the difference. The process was carried out as follows: The scales were removed, 
cleaned, and decalcified until no more mineral matter was removed by the 0.5 per cent 
HC1 used. The residual scales were washed free from chlorides with water, then 
with alcohol and ether, and dried to constant weight at 105 1 C. The dry organic 
matter so obtained was weighed, and digested with a large excess of 0.1 per cent HC1 
at 40 to 45° C. for 12 days. Thymol was used to prevent, putrefaction. The residual 
ichthylepidin was filtered off, washed thoroughly with water, alcohol, and ether, and 
dried at 105° C. The loss in weight which the organic matter had suffered was taken 
as collogen. 
17.7950 grams of dry organic matter from menhaden scales left a residue of 
4.2255 grams (ichthylepidin) when treated as described above. 
8.1550 grams of dry organic matter from shad scales left a. residue of 1.9570 grams. 
Menhaden. 
Sliad. 
Per cent. 
23.74 
76.26 
Per cent. 
24. 00 
76. 00 
The two species thus have nearly the same relative organic composition, and the 
numbers found are in close agreement with Morner’s estimations. It seems that the 
ratio between the amounts of the two albuminoids is nearly constant in various fish 
whose scales contain ichthylepidin. 
It may be remarked that a great difference exists (apparently) in the collogen of 
scales containing no ichthylepidin and those containing the latter substance. In the 
latter case the collogen is very loosely combined (also noticed by Morner), a large 
