464 Miscellaneous. 



By the kindness of M. Guy, who is successfiilly rearing a pair of 

 Macropodce in his magnificent aquarium of the Faubourg Saint- 

 Cyprien, I have been able to study, not only the nidification of this 

 handsome fish, but also its ova and their development, which is so 

 rapid that I have seen them hatched in sixty hours. I shall not 

 enter into long details as to the embryogeny of our Macropodce, as I 

 have the intention of soon making known all its phases, with numerous 

 drawings to illustrate them. It will be sufficient at present to say 

 that the development of our little Chinese fishes presents much 

 analogy with that of the perch, which was so well studied by our 

 colleague LerebouUet. I shall therefore at present confine myself 

 to the most striking features. 



The ovum of the Macropoda, which is of the size of a poppy-seed 

 at the time of its being deposited, is distinguished by its perfect 

 transparency and its density, which is inferior to that of water. 

 Hence it rises of itself to the surface and comes into contact with the 

 air-bubbles which compose the nest fabricated by the male, or which 

 are expelled from his mouth when he respires. "We have already 

 stated that the embryogenic work which has to be accomplished 

 within the ovum does not last longer than from sixty to sixty-five 

 hours ; but rapid as the hatching is, it is not more so than that of 

 the tench and some other fishes. But it wiU be easily understood 

 that, in consequence of this rapid developmemt, the animal must be 

 born in a very imperfect state. In point of fact it presents the form 

 of an obese tadpole, the head and trunk of which are applied to an 

 enormous umbilical vesicle, whilst the tail is free, already very 

 mobile, and furnished aU round with an extremely transparent 

 natatory membrane. 



Although it appears to be completely destitute of striated muscu- 

 lar fibres, the animal wriggles briskly upon the object-slide. It 

 is about 11 miUim. in length. 



Its head is remarkable by the existence of two large eyes still 

 destitute of pigment. The mouth does not yet exist. This is also 

 the case with the intestine and the anus. But the heart has already 

 been in motion for more than twelve hours, and there is an active 

 circulation in a part of the tail (nearly the anterior half), in the 

 vitelline vesicle, and in the remainder of the body. There are no 

 branchise ; the respiration is efi'ected by means of the skin and the 

 umbilical vesicle ; there are no secretory organs of bile or urine, no 

 genital organs, and no fins properly so called. 



As in aU fishes and, indeed, in aU Vertebrata, the nervous system, 

 which is very early formed, consists of two parallel cords which swell 

 out in the head to give origin to the cerebral vesicles. The skeleton 

 is as yet represented only by the chorda dorsalis ; the vertebral 

 laminae, if they exist, are not yet very distinct. 



Numerous pigment-spots are to be seen upon all parts of the body, 

 and even upon the umbilical vesicle. 



Many organs which do not yet exist will appear sooner or 

 later after birth. Of this number are the mouth, the intestine, the 

 liver, the swimming-bladder (at least in the perch) ; the genito- 



