TRANSMISSION OF MALFORMATIONS. 195 
from which this fish was taken should be dragged for 
the purpose of ascertaining the existence of other fish 
similarly affected. When this was 
done several fish of the same 
species were taken with tumours 
of the same kind growing upon 
them. 
In this case it is reasonable to 
suppose, in the absence of evidence 
to the contrary, that the inhabi- 
tants of the pond being limited, 
the chances of this defect being 
transmitted were greatly in- 
creased. This view is equally 
applicable to the case of the tail- 
less trout of Islay. 
The curious condition of the 
skeleton of the fish Chetodon, 
described by William Bell in the 
“Philosophical Transaction,” 1793, 
deserves mention in connection 
with this subject. He writes :— 
“The fish is frequently caught at 
Bencoolen and several other parts 
on the west coast of Sumatra. 
The skeleton is very singular, 
many of the bones having tumours, 
which in the first fish Mr. Bell saw 
FIG. 105.—A bone from the fish 
Chzetodon with a tumour, 
shown in section, attached 
to it. (Nat. size.) 
he supposed to be exostoses arising from disease, but 
on dissecting a second found the corresponding bones 
had exactly similar tumours, and the fishermen informed 
