98 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
after being carefully freed from adhering tissue, were thoroughly scrubbed with 
water and washed by decantation until the water remained perfectly clear. The clean 
scales were then twice extracted with a large excess of 0.5 per cent hydrochloric 
acid (real HC1), each extraction lasting 12 hours. The scales were then washed with 
water until free from chlorides and finally tested for ichthylepidin as mentioned above. 
In some cases, where the scales could not be removed mechanically, the integument was 
dissolved by dilute (5 per cent) sodium hydroxide, and the scales so separated were 
then treated as above described. Morner found ichthylepidin to be unchanged after 
several days’ exposure to 5 per cent sodium hydroxide. We confirmed this fact by 
ti’eating some menhaden scales with the alkali for three days, after which the presence 
of ichthylepidin was detected as readily as before. It was found necessary to treat the 
integument of all the elasmobranehs, the sun-fish (Mold mold), the puffer {Spheroides 
maculatus) , and the remora ( Echeneis ncm crates) with 5 per cent alkali. 
The scales of the following fish gave positive reactions for ichthylepidin when 
treated as described above: 
1. Winter flounder (. Pseudopleuronecles amer- 
ica.nus). 
2. Alewife (Pomolobus pseudoharengus). 
3. Blue-fish (Pomatomus saltatrix). 
4. Hickory shad [Pomolobus mediocris) . 
5. Chogset ( Tautogolabrus adspersus) . 
6. Butter-fish (Rhombus triacanthus). 
7. Tarpon ( Tarpon atlanticus) . 
8. Mackerel scad (Dccapterus macarellus). 
9. Sea robin (Prionotus carolinus) . 
L0. Salmon ( Salmo salar). 
11. Cod (Gadus callarias). 
12. Haddock (Melanogrammus seglifinus) . 
13. Crevalle ( Caranx crysos ). 
14. Summer flounder ( Paralichthys denlatus). 
15. Menhaden (Brevoortia tyr annus). 
16. Tile-fisli ( Lopholatilus cliarnicleonticeps ) . 
17. Squeteague ( Cy noscion regalis). 
18. Bonito (Sarda sarda) . 
19. Soup (Stenoiomus chrysops). 
20. Hake ( Phycis chuss). 
21. Sea bass (Centropristes striatus). 
22. Silverside (Menidia notata) . 
23. Striped minnow ( Fundulus majalis) . 
24. Tautog (Tauloga onitis). 
25. Mummichog (Fundulus heteroclitus) . 
26. Remora (Echeneis naucrates). 
27. Rudder-fish ( Palinurichthys perciformis) . 
28. Common shad (Alosa sapidissima). 
29. Sturgeon (Acipenser sturio). 
30. Perch ( Morone americanus) . 
31. Jumping mullet (Mugil ccphalus). 
32. King-fish (Menticirrhus saxatilis) . 
33. Broad minnow (Cyprinodon variegatus). 
In all the above cases the reactions given by Millon’s reagent were very marked, 
the red coloration being brilliant. The darkening caused by warming with the lead- 
alkali solution was very variable in intensity. This reaction was strong in Nos. 3, 
11, 20, 21, 22, and 29 of the above list, very faint in Nos. 1, 11, 15, 27, and 28, and 
in the other cases ranged between the two extremes. 
It is interesting to note that the ganoid scales of the sturgeon ( Acipenser sturio ) 
gave strong reactions with both Millon’s reagent and with the lead-alkali solution, 
although Morner, as above noted, found the ganoid scales of the gar-pike ( Lepisosteus 
osseus) to give negative results with these reagents. In our experiments the scales 
were taken from the median portion of the “lateral line.” They were extracted with 
5 per cent HC1 for 5 days, washed free from acid, and extracted with 0.05 per cent 
caustic potash in excess and again washed. After reextraction with 0.5 per cent 
HC1 for 2 days, the scales were given a final washing and submitted to the tests for 
ichthylepidin. 
In the remora (No. 26) both the scales and “sucking disk” were examined. The 
scales were obtained by digesting the integument with 5 per cent caustic soda for 36 
hours (in the cold). The scales so removed were variable in size and shape; they 
were cycloidal, usually long and narrow, and were mostly pointed at one end and 
