iSo 



TENTH ANNUAL REPORT OF THE 



was at first that all the ulcerative lesions originated beneath the skin and 

 involved the skin by eroding it in an ectal direction. This is certainly not 

 always the case. The incipient ulcer may sometimes be seen as a shallow 

 pit in the skin which had not yet been broken through to the muscle. 

 In such cases it must have started either on the surface or within the 

 skin. 



During the latter part of the stages of the disease, ulcers were seen in 

 a healing condition. A thin, smooth layer of tissue, full of pigment cells, 

 but without scales, had proliferated over the bottom of the ulcer; and, 

 without doubt, some few trout, at one time having a typical infection with 

 the usual lesions, resisted the disease and passed to complete recovery. 



The following estimations of hemoglobin in dying trout were made 

 from samples of blood obtained by puncture of the dorsal aorta. The Dare 

 hemoglobinometer was used. The readings are on a basis of ioo as repre- 

 senting normal human blood: 



TOTAL LENGTH OP TROUT IN INCHES. 



SEX. 



HEMOGLOBIN. 



8.0 



8-5 



7-5 



13° 



10-25 



5-75 



6-5 . 



10 . 



Male 



Female .... 



Male 



Male 



' Male 



Male 



Female .... 



35 



46 



8 



47 

 S^ 

 3 1 

 IS 

 27 



Average hemoglobin 

 30.6 



It does not appear from these readings that any marked anemia char- 

 acterizes the disease. The average of the eight specimens is 30.6. Twenty 

 readings of the blood of healthy domesticated brook trout of the Michigan 

 Fish Commission, at Paris, Mich., average 35. There is quite a wide varia- 

 tion among individuals, apparently perfectly normal. Of the eight diseased 



