354 



SALMON AND TROUT. 



it has altered very little in appearance from the new-born 

 larva. 



Before treating of the next change, from nymph to sub- 

 imago, there are two points requiring consideration, and on 

 these two points, unfortunately, very little reliable informa- 

 tion can be obtained. They are -firstly \ the length of time 

 intervening between the depositing of the eggs and the appear- 

 ance of the winged subimago on the water ; and secondly : the 

 nature of the food on which the insect subsists during the 

 larval and nymph stages. 



When, with the kind assistance of a friend, I first succeeded 

 in hatching May-fly eggs in captivity, we entertained strong 



hopes of being able to work out 

 these two important questions 

 of the life-history. Much time 

 was consumed in daily micro- 

 scopic examination of the eggs 

 as the gradual development of 

 the embryo proceeded. To 

 provide as far as possible in 

 captivity the same circumstances 

 and the same surroundings as 

 the larvae would have experi- 

 enced in the natural state, mud, 

 gravel, and weeds from the river 



were distributed in the troughs in which the eggs were hatch- 

 ing. A grave cause of anxiety was that, of course, we could 

 only use London water, and very possibly in the filtration which 

 it undergoes the most necessary food for the young larvae might 

 be removed. All our efforts, however, were in vain. In a few 

 weeks, out of many hundreds of thousands of eggs hatched 

 not a single living specimen could be found. 



Although much disheartened at this first failure, and having 

 been in two consecutive seasons since prevented from trying 

 the experiment again, I do not confess myself beaten, and fully 

 expect some day to succeed in rearing full-grown May-flies from 



LARVA. 



