132 FISH HATCHING. 



of the salmon when it was under the glass, 

 and ascertained that it averaged about 

 seventy in a minute. My friend, Mr. Hall, 

 of Farningham, has made observations on 

 the pulse of one of his young trout. He 

 reports that, on April 6th, when the fish 

 was just hatched out of the ovum, the pulse 

 was eighty per minute. On the 13th it was 

 ninety-five, and on the 1 7th, one hundred-and- 

 twelve per minute. Just below the heart can 

 be seen on the umbilical vesicle (when the 

 fish is in the water) a bright red streak ; 

 examine this under the microscope, and you 

 will see that this red streak is in fact a main 

 artery ; with a high power, you can see 

 plainly the minute blood-discs coursing along 

 between the walls of this elastic tube. The 

 minor red streaks upon the umbilical vesicle 



