STORMONTFIELD EXPERIMENT. 41 



from the deposition of the last of the ova. A 

 high or low temperature of the water will accele- 

 rate or retard the hatching; ova have been 

 hatched by us in 60 days, in a constant tempe- 

 rature of 44 degrees, but in the rivers in this 

 latitude from 100 to 140 is the time, according 

 to the season. 



We were furnished with a few ova, and, by 

 keeping up a supply of pure water we were 

 gratified by observing the little creature burst- 

 ing the shell. The fish lies in the shell, coiled 

 round in the form of a bow, and the greatest 

 strain being at the back, it is the first part 

 that is freed; and, after a few struggles, the 

 shell is entirely thrown off with a jerk. The 

 appearance of the fish at this stage of its being is 

 very interesting; what is to be the future fish is a 

 mere line, the head and eyes large, the latter very 

 prominent. Along the belly of the fish, from the 

 gills, is suspended a bag of large dimensions in 

 proportion to the size of the fish. This bag con- 

 tains a yolk which nourishes the fish for six 

 weeks, after which they must be fed. For a few 

 days after hatching, the two dorsal fins are ap- 

 parently joined, and the two pectoral are very large 

 in proportion to the rest of the animal. The little 



