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A PARASITIC DISEASE IN THE HADDOCK 
{Gadus aeglefinus) 
By J. W. W. STEPHENS, M.D., D.P.H., and RUBERT BOYCE, M.B., F.R.S. 
ON October 23, 1903, a smoked haddock (from Grimsby) was sent to the 
Bacteriological Department tor examination. It was seized by one of the 
meat inspectors as it appeared to him that the muscle of the fish was abnormally 
pale and that the ' curing ' had not been properly carried out. 
Upon examination we found, scattered throughout the substance of the muscle, 
numerous small white specks which forcibly reminded us of the appearance of encysted 
trichinae in muscle. In Fig. r, a photograph, natural size, made from a thin slice of 
the muscle, the appearances of the specks are well seen. They are spindle shaped, 
two or three times longer than broad, they vary in length from a speck just visible to 
the naked eye to a body one-twelfth to one-eight inches long ; their long axis is 
parallel to the direction of the muscular fibres, and they are opaque white in colour, 
contrasting with the transparent muscular fibres. Portions of the tissue were hardened 
in mercuric perchloride and in formol in the usual manner, and carefully embedded in 
paraffin. The sections were stained by several methods, and included haematoxylin 
and eosin, methylene blue, carbol fuchsine and methylene blue, erythrosin and 
methylene blue, and Romanowsky. For the preparation of the sections we are 
indebted to the assistance of Dr. Fred. Griffith (Alexander Fellow). 
When one of the spindle-shaped bodies is examined under the low power, and 
after staining, as in P ig. 2, it is seen to be composed not of one single parasite but of 
what appears to be very numerous minute unicellular encapsuled bodies infiltrated 
between the muscular fibres. They are clearly in the intermuscular fibrous tissue, but 
they press into the muscle fibres, and the muscle fibres in their midst are in advanced 
degeneration. At first sight the curious homogeneous appearance of the spindle body 
might lead one to suppose that one had to deal with a comparatively large and complex 
parasite, and that the unicellular bodies were ova, but careful examination shows no 
evidence of complex structure, and, moreover, that the margin of the spindle-shaped 
body is not encapsuled by a definite body wall, and that irregular ramifications of the 
mass extend into the surrounding intermuscular tissue. The spindle body is a necrotic 
focus in the muscle produced by the invasion of what appears to be a unicellular 
parasite. It must always be borne in mind that the description of the sections is con- 
ducted under difficulties, for the structure cannot be as well preserved by smoke curing 
as by proper laboratory methods of fixing ; for instance, there was abundant evidence 
throughout the sections of bacterial infection, colonies of cocci having penetrated 
in many directions between the muscular fibres. Nevertheless, the tissue elements 
