THK NEW AKT OF BREEDING FISH. 147 



umbilical vessel is known to nourish other embryo 

 animals. By the end of fifty days, or the 30th of 

 May, the bag contracted and disappeared. The fin 

 or tadpole-like fringe also disappeared by dividing 

 itself into the dorsal, adipose, and anal fins, all of 

 which then became perfectly developed. The little 

 transverse bars, which for a period of two years (as I 

 have already shown) characterize it as the parr, also 

 made their appearance. Thus, from the 10th of 

 January till the end of May, a period of upwards of 

 140 days, was required to perfect this little fish, 

 which even then measured little more than one inch 

 in length, and corresponded in all respects with 

 those on which I had formerly experimented, as well 

 as with such as existed at that same time in great 

 numbers in the natural streams." 



Mr. Shaw afterwards made additional experi- 

 ments in ponds artificially constructed, of which the 

 following is a description : — 



"The ponds, which are three in number, are 

 two feet deep, and thickly embedded with gravel, 

 while they are at the same time supplied with a 

 small stream of spring water in which the larvae of 

 insects abound. Pond No. 1 is 25 feet in length by 

 18 in breadth, and is fed by the stream which de- 

 bouches into it at the fall F. Pond No. 2 is 22 

 feet in length by 18 in breadth, and is fed from 

 pond No. 1, at G, where the communication is care- 

 fully grated with wire. Pond No. 3 is 50 feet in 

 length by 30 in breadth, and is fed by the stream 



