BULLETIN OF THE UNITED STATES FISH COMMISSION. 345 



171.— ivoTc: orv the rgceneratioiv of the scales of the oer. 



ma:\ carp. 



By JOHN A. RYDER. 



In the early part of 1884 a fine specimeu of the German carp, of the 

 mirror variety, was brought from the carp ponds to the Armory Buikl- 

 iug, where it was placed in one of a number of large aquaria. Unfor- 

 tunately in handling- the specimeu, which is now nearly 18 inches long 

 and 5 inches wide, one of the largest scales of the large lateral series 

 was knocked off, so that after a careful examination the writer expressed 

 himself satisfied that the injury received by the fish was considerable, and 

 that there could be no doubt that nothing of the scale remained, though 

 it is probable that the '' bed " or tissue from which the scale grew was 

 preserved, but the outer investment of the scale was almost altogether 

 gone. The scale in question was situated just behind the right oper- 

 culum, and was nearly or quite an inch wide vertically. 



Dr. K. Hessel, who was present when the scale was knocked off of 

 the fish, picked it up and kept it. There is therefore no doubt whatever 

 that it was wholly removed. 



After abQut five months have elapsed, or at the time of the present 

 Tvriting, an examination shows that a new scale has been formed in the 

 situation where the first one grew, similar in form to the old one, but 

 apparently thinner, the outer skiu investing it being also less densely 

 pigmented than that which covers the scale in a corresponding position 

 on the opposite side of the body. 



When the scale was first lost the surface from which it had been 

 removed was congested, though the irritation in the vicinity seemed 

 to subside after a fortnight or thereabouts, so that but little evidence 

 of the injury remained, except the whitish appearance of the skin 

 where the scale was originally situated. It is still lighter in color, but 

 is otherwise perfectly healthy, though the fish had been tor a time 

 infested with fungus, from which it recovered entirely, in spite of the 

 fact that an abraded surface was exposed which would render it more 

 liable to succumb to the inroads of the vegetable parasite. 



To what extent the scales of fishes may be regenerated, and under 

 what conditions, the writer is not able to say, but there is no doubt 

 ^vhatever that such regeneration sometimes occurs, as in the case cited 

 above. Without taking the trouble to look u^) the literature relatiur 

 to the regeneration of the scales of fishes, of which there does not, so 

 far as he is aware, seem to be much, the writer has thought the fore- 

 going well authenticated case of the regeneration of these structures 

 worthy of record, so that others might be profited in case it should 

 be desired to investigate the subject still farther. It is doubtless true 

 that, as in the case of the nails, where if the underlying epidermis 



