MAY-FLY FISHING. 355 
eggs hatched in captivity. It is perhaps some encouragement 
‘to find that Pictet, who spared neither time nor trouble in 
carrying out his most valuable experiments and observations, 
and who, besides, lived in Geneva, with an inexhaustible supply. 
of pure water from the lake and the Rhone at his door, seems 
equally to have failed in thisrespect. He says: ‘Tlest difficile 
d’avoir des idées précises sur le temps qui s’écoule depuis la 
naissance des larves jusqu’a leur métamorphose. Swammerdarn 
donne aux larves de la Palingenia longicauda une durée de 
trois ans, et Réaumur pense que celles de la P. virgo vivent 
deux ans. Je n’ai pas pu faire sur ce sujet des observations 
directes, parce que les larves de 7 Ephemera vulgata, les seules 
que j’aie pu observer moi-méme dans cette division des larves 
fouisseuses, sont trés difficiles 4 élever longtemps, et que je 
n’ai jamais pu les conserver plus de quelques mois.’ 
There are, however, sufficient data to justify the positive 
statement, that not less than two years elapse between the 
laying of the egg and the appearance of the winged subimago 
on the water. Every year since 1886 I have searched in the 
mud during the drake season, and have invariably found two 
sizes: one, quite near the surface—the nymph just on the 
point of changing to the subimago—and the other, much deeper 
in the mud, a half-grown larva without any trace of wing-covers. 
In no single instance was a larva found either in an inter- 
mediate stage or smaller than the half-grown specimens, and 
hence the evidence may, I think, be deemed sufficient to esta- 
blish the fact that the time occupied in the growth of the 
winged insect from the egg is two years, and no more. 
As to the food question. FPictet declares that he has dis- 
covered remains of small insects or aquatic worms in the 
alimentary canal of the larve. An earlier authority—Swam- 
merdam—says that he has only found ‘terre glaise,’ or clayey 
earth. Pictet’s observations are, as a rule, so accurate and so 
reliable that it would be an act of presumption on my part to 
cast the least shade of doubt on any word he has written, yet, 
as far as my own experience has gone, a number of autopsies 
AA2 
