85 
The Scales of Fish. 
By \V. A. Willes. 
Delivered as a General Lecture at Trinity Hall, March 29th, 1913, 
mHE examination of fish scales with the aid of the microscope 
is no new study. So far back as the sixteenth century it 
is recorded that soon after its invention a man named 
Borello wrote a brief description of the microscopic 
appearance of a fish-scale, but nothing seems to have been done 
in this direction with regard to salmon and trout until recent 
times, when Messrs^ Calderwood and Johnston, of the Scottish 
Fishery Board, Mr. J. Arthur Hutton, so well-known for his 
excellent work in the restoration of the River Wye to the position 
of a first-class salmon river, and others took the matter up, 
and, by a systematic series of research experiments conducted in 
parts of Scotland, obtained such a valuable insight into the life 
and habits of the salmon, as to make the study of its scales a 
most interesting and important work, inasmuch as by this study 
the whole life and habits of a salmon can be identified. 
This research work has been the means of upsetting many 
theories formerly held, and should be the groundwork for future 
legislation in restoring our rivers to their former productiveness, 
and by this means, adding to the food of our country. In 
considering fish-scales let us first of all try and get a good 
definition of a fish—surely it is a vertebrate animal which lives 
in water, and breathes liquified oxygen by means of its gills, 
wherewith it oxygenates its blood. Then, what is a scale? This 
word, as we all know, has different meanings in our own 
language. We use it in the sense of climbing, in the sense of 
a balance, in the sense of harmonic or musical proportion, and 
in the sense of the outer covering of a fish; but in all its various 
applications it seems to be derived from a Saxon word signifying 
to divide—so that the scale of a fish is a divided thing, a part 
of a whole. 
The scale of a fish may be described as a little thin transparent 
plate, and upon this plate is engraved, so to speak, the whole 
history of the fish—more particularly of the salmon and trout. 
These scales are embedded in little pockets of the skin of the 
fish—so far as regards two-thirds of the scale—the remaining 
one-third being the exposed portion, which is what you see on 
the fishmonger’s slab. The hidden portion is called the Anterior, 
and the exposed portion the Posterior part of the scale. 
The use of these scales is undoubtedly to preserve the body 
of the fish from the attacks of the numerous parasites which infest 
salt water, and in order to do this effectually, and to make what 
a workman employed on slating the roof of your house would 
call “ a tight job,” these scales overlap one another—just like 
the tiles of a house. Now, underneath the scale of a salmon, 
