
THE PROPAGATION OF THE GOLDFISH 

cently fertilized ova of the pike, of almost entire broods of salmon com- 
posed of fry developed as double and triple monsters, each from a single 
yolk, by rough and careless handling or shaking of the ova during the 
early stages of their development; and the production of double monsters 
of the lobster and of birds by these and similar treatment of the eggs; 
which led him to the conclusion that the double-tailed goldfishes were 
produced by this or similar simple practices. The Orientals, by taking 
the eggs of the normal species and either by shaking or disturbing them in 
other ways produced some complete double monsters, some with two 
heads and a single tail, and some with duplicate caudal and anal fins. Of 
these the double monsters did not survive, but those with duplicated fins 
may have been kept alive and selections in breeding would continue the 
tendency to double fins. 
It is known that crustaceans, batrachians, reptiles and fishes also 
have the power not only to reproduce lost parts, but of their regeneration 
in duplicate and triplicate, diverging from the point of mutilation. In tad- 
poles it has been observed that when the tail is cut off at right angles to the 
body, the new tip grows straight backwards in normal form, but when the cut 
is at an acute angle the development is, according to the inclination, either 
upwards or downwards; and that, if the growth of new material is inter- 
fered with across the narrow line of the stump, the growth will be to each - 
side, producing a duplication of the part in diverging directions. 
It has also been noted that this regenerative power diminishes in the 
higher animals, the last evidence being the reproduction of extremital parts; 
and that the rarity of the production of monstrosities, due to disturbance 
during the development, also diminishes, so that the continuation of these 
aberrations in successive generations becomes less frequent in the higher 
animal forms. 
With fishes, however, the hereditary tendency to duplication of parts 
is a marked characteristic; and the goldfish and other Cyprinidae tend to 
the retention of abnormalities; but which, in the natural state of pond ex- 
istence would be lost,as fishes encumbered with duplicate fins, especially tails, 
would be less likely to reach maturity than those normally developed, though 
this sometimes occurs. Under the care of the breeder, however, these are 
fostered and by selection and careful propagation still further developed, 
until this tendency becomes a characteristic of the breed, and a considerable 
portion of the young continue the desired inherited peculiarity. 
How this tendency is transmitted to the ova of the parent it is difficult 
to trace, but it is certain that the partially double bodies of the parents 
have some influence, and that the artificial interference with the ova or 
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