AN INSECT'S PULSE. 407 



head by the regular contractions of its side. This 

 causes the beating movement which we saw in the 

 caterpillar. Perhaps there may be some curiosity 

 to know whether an insecfs pulse beats faster or 

 slower than ours. John Hunter counted thirty- 

 four beats in a minute in a silk-worm. Another 

 observer counted thirty a minute in a caterpillar 

 of the pine-moth. But in the imago state the pulse 

 appears to move much quicker : and it is easy to 

 make an insect's beat extremely fast, by exciting or 

 provoking it. Mr. Newport having done so to a 

 bee, counted as many as 142 beats a minute. In 

 a middle-aged man the pulse beats about seventy 

 times in a minute ; in a child seven years old about 

 eighty-five times ; and at the age of fourteen about 

 eighty times. Hence it follows that our pulse beats 

 about twice as fast as that of an insect in the 

 larva state : in the imago state it is probably, as a 

 general rule, at least in winged, active insects, 

 higher than ours. 



