On Double Monstrosity in Fishes. 47 



V^. — On Double Monstrosity in Fishes. 



On the 19th March last^ M. de Quatrefages exhibited to the 

 French Academy of Sciences a hving specimen of a double mon- 

 strous Fish. The observations made by M. de Quatrefages on 

 the occasion of this exhibition have given rise to a discussion 

 upon the phsenomenon of double monstrosity in Fishes, in 

 which several of the most distinguished physiologists of France 

 have taken part, and although, as might be expected from the 

 nature of the subject, no very decisive results have been ob- 

 tained, there seems to be every reason to hope, from the zeal 

 with which these gentlemen appear to be devoting their atten- 

 tion to the solution of the interesting question of the mode of 

 production of these monstrosities, that their researches may 

 eventually throw considerable light, not only upon the particular 

 phsenomenon in question, but also upon the origin and deve- 

 lopment of the normal embryo. For this reason we have thought 

 it advisable to give a short account of some of the leading state- 

 ments that have been made, in the hope that by so doing we 

 may call the attention of some of our readers to this interesting 

 subject. 



The monster exhibited by M. de Quatrefages had been ob- 

 served by him for a period of nearly two months. When he first 

 received it, it consisted of two young fishes, completely separated 

 from each other and adhering to the opposite sides of a vitellus, 

 which exhibited a deep notch in front. Each of these embryos 

 exhibited a certain amount of deformity, — one, the largest, had 

 the face deformed and the eyes entirely wanting, whilst the other 

 parts of the body were perfectly developed ; — in the other the 

 head was well-formed, the body humped and the tail twisted. 

 The two abdominal veins (afterwards converted into the vencz 

 j)ortai) were in their usual position, and their ramifications 

 spread over the whole surface of the vitellus, communicating at 

 their extremities with the roots of the vitelline veins, which 

 afterwards form the hepatic veins. It is remarkable also that 

 numerous anastomoses united the last ramifications of the abdo- 

 minal vein of each embryo with those of the vitelline vein of the 

 other, so that a continual interchange of blood took place. [Ac- 

 cording to M. Coste the circulation in double monsters is common 

 to the two embryos, — the greater part of the blood which has 

 circulated in the body of one passing into the vessels of the um- 

 bilical vesicle [abdominal vein], whence the greater part of it is 

 conveyed by the vitelline vein to the auricle of the other embryo 

 and so on, and in accordance with this reciprocal circulation 

 the contractions of the two ventricles take place alternately. 



