INVERTEBRATES OF LAKES GENEVA AND MENDOTA. 
483 
During the first two or three days it was not difficult to find floating on the lake, 
among hundreds of putrescent bodies, now and then one which presented a fairly fresh 
appearance, the gills unaltered, the eyes not sunken, and the color bright. During 
many hours rowing, however, I saw but two perch in the act of dying and succeeded 
in capturing but one. The actions of these perch were precisely those described by 
previous observers as characteristic of the death struggle of the diseased fish. They 
were at the surface, fluttering their fins, spinning irregularly about or scarcely moving 
at all, often gasping as if for breath, rolling over on their sides or backs between 
convulsions, and occasionally, for a few moments, disappearing from sight or swim- 
ming feebly and irregularly along. The single sick fish captured, I took while it was 
still struggling, but it scarcely moved after it was landed in the boat. Slides of the 
blood of this fish, taken with a pipette from the auricle of the heart and from the 
venous sinus, were at once prepared, and its viscera were placed in 94 per cent, alco- 
hol within a half hour of its death. I made similar preparations of the fluids and 
organs of other perch that had died of the disease — the freshest I could obtain — and 
dissected twenty-four of them for a study of the contents of their alimentary canals. 
In preparing the blood, I used the common method of making slides for bacteriolog- 
ical study, drying rapidly upon a cover glass a thin film of the blood, flaming it in the 
blaze of an alcohol lamp, staining with a glycerine solution of methyl violet or of 
Bismark brown, and mounting in Danada balsam. 
The general appearance of recently-dead specimens was that of a healthy fish. 
They were, almost without exception, in good average condition, often fat and plump; 
a fact noticed with astonishment by all who gave the matter any close attention. The 
color was always bright, and the surface everywhere clean, and without a trace of fun- 
gous attack. The gills were very commonly congested, but not appreciably more so 
than those of a fish dying in the air. Their mucous membrane was seemingly always 
quite uninjured, and was certainly so in several specimens of which I examined the 
filaments microscopically ; and there was no trace of parasitism, fungous or animal, 
in the gills of any fish I took. The heart was always distended with blood and some- 
times so gorged that the bulging of the venous sinus was visible from without. The 
liver was likewise congested, but seemingly by mechanical causes, as its tissues gave 
no evidence of infiltration. The blood itself was normal, the corpuscles in perfect con- 
dition, and both they and the plasma free of bacteria. The alimentary canal pre- 
sented no unusual appearance, and was commonly fairly well filled with food, much 
of which had evidently been eaten rather recently. Many of the large Chironomus 
larvae, which composed the greater part of it in every case but one, were entire and 
still retained their dark red color. 
Concerning the histological condition of the principal tissues of the diseased perch 
I have unfortunately very little to report. My removal during the autumn of 1884 from 
Normal to the University of Illinois at Champaign, and the consequent transfer of 
the laboratory equipment and collections under my charge, made it impossible for 
me then to prepare and mount the material obtained for histological study, and this 
was kindly undertaken for me by a microscopist in Chicago. From him I received 
later a good series of sections of liver, spleen, heart, brain, kidney, stomach, and in- 
testine of the lake herring, but all the material from the single perch taken alive was 
destroyed by an unfortunate accident while in his possession, and I had left for study 
