PROGRESS IX BIOLOGICAL INQUIRIES. 15 



is not primarily responsible in c'ausin<; white si)()t as it is coinnKinly 

 seen tlurin<r hatching: operations, and European observers who have 

 rei^orted it seem to have had exce])tional cases. Mention may be 

 made of a still different form of the disease in Alaska, of which only 

 superficial investigation has been made. 



Work Avas started on the stuily of ovarial conditions in various 

 fislies. especially at time of spawning. It is this phase in the various 

 activities of fishes which bears directly on tlie problems of sterility, 

 production of " glassy " ova, hardening of ovaries w^hen retained in 

 ]>ens or crates, and effect of stripping. The nature of the problem 

 makes the work on it more or less sporadic. 



The troublesome question of the great mortality in hatching pike- 

 j^erch eggs is under investigation at present. A visit was made to 

 hwanton, Vt., at the time of spaw^ning, to observe conditions in the 

 field. In spite of the fact that the problem is an old one, it seems 

 that no definite analysis of the morphological features of affected 

 eggs has ever been made. Consequently the few remedial measures 

 employed have been of little or no advantage. The essential studies 

 are now in progress. 



FISH DISEASE IX ST. LAWRENCE RIVER. 



While mortality of fish in natural waters as a result of disease is 

 not usually conspicuous, nevertheless there are occasions when such 

 occurrences demand attention. An investigation of an epidemic 

 among the fish in the St. Lawrence River at Ogdensburg, N, Y., was 

 made during the first week in July, hj Prof. H. S. Davis, temporary 

 investigator. The superintendent of a New York fish hatcher}^ had 

 reported that large numbers of fish were dying in the ponds and 

 also in the river. 



The epidemic was at its height during the first two weeks in June 

 and then decreased rapidly in severity. At the time of the investiga- 

 tion the disease had entirely disappeared from the ponds and only a 

 few diseased fish were taken in the river. None of these appearecl to 

 be seriously affected. 



The fish taken in the river showed two distinct types of lesions on 

 the skin. On the bullheads and catfish the infected areas were very 

 distinct, about one-half to 1 inch in diameter and bright red in 

 color, due to the complete destruction of the epidermis, thus expos- 

 ing tlie inflamed dermis beneath. 



The diseased areas in the skin of bass and suckers had a very dif- 

 ferent appearance. They were irregular in shape and so indistinct 

 as to attract attention only on close examination. The most marked 

 characteristic w\ts a faint reddish border around the scales, due to a 

 slight extravasation of blood into the epidermis. 



A microscopic examination of sections of skin from the infected 

 areas indicates that the disease in bullheads and catfish is probably 

 distinct from that in the bass and suckers. In the former the disease 

 is apparently due to bacteria, which are present in enormous numbers 

 in the disintegrating epidermis. These bacteria are not present in 

 the lesions on bass and suckers, and the cause of this affection is at 

 present problematic. A further report may be made. 



51700°— 21 7 



