MA Y-FLY FISHING. 355 



eggs hatched in captivity. It is perhaps some encouragement 

 to frnd 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 this respect. He says : 'Ilest difficile 

 d'avoir des idees precises sur le temps qui s'ecoule depuis la 

 naissance des larves jusqu'a leur metamorphose. Swammerdarn 

 donne aux larves de la Palingenia longicauda une duree de 

 trois ans, et Reaumur 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 F Ephemera vulgata^ les seules 

 que j'aie pu observer moi-meme dans cette division des larves 

 fouisseuses, sont tres difficiles a clever 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. Pictet declares that he has dis- 

 covered remains of small insects or aquatic worms in the 

 alimentary canal of the larvae. 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 



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