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 ofextremltal 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 



9+ 



