114 REPORT OF THE COMMISSIONERS OF 



Mr. Armistead has this also to say about Cyclops previously figured in this paper. 

 "The great importance of these creatures will be understood, when we consider that 

 it has been estimated that a single female may be the origin of over four hundred 

 millions of its species in one year; nay, according to a calculation by Jurine, a single 

 Cyclops is capable of producing over four billions in the course of a single year. The 

 calculation is based on the assumption that all live and go on producing, but in reality, 

 such an occurrence never takes place, as there are so many predacious animals which 

 prey upon these crustaceans, that few of them practically survive. These figures, how- 

 ever, have their lesson. They teach us of the enormous possibilities that exist with 

 regard to the increase of these minute creatures, where by so-called artificial means 

 they can be protected from their enemies and allowed to multiply enormously. The 

 food of Cyclops is produced by decaying vegetable matter, and minute spores." 



While looking over the authorities to find what, if anything, had been said on the 

 subject of minute crustaceans for fish food, quite by chance I found a review of a new 

 book in the Fishing Gazette, London. The title is " Animals at Work and Play," and 

 the author is C. J. Cornish. One chapter is devoted to "The Invisible Food of Fishes," 

 and in it the author says : 



"The microscopic creatures which are in parts of the Atlantic massed so thickly in 

 the water as to discolor the surface and give abundant food for the whale, are present 

 not so thickly, but in numbers comparable to motes in the air, in all parts of the sea. 



* * The upper waters of the sea are in fact a nutritive soup teeming with food exactly 

 suited to their (the fishes) need. These microscopic creatures are the basis of all the 

 larger life of the ocean, and in a great degree of the growth and increase of fresh water 

 fishes. Some of these tiny creatures are' water-fleas, others, like carpaced shrimps, are 

 of prodigious fecundity. In rivers they are almost the sole food of all young fish, and 

 probably the main resource of the older fish when other supplies fail. In the first days 

 of spring the creatures in every stage, eggs, larvae, and perfect, though microscopic 

 entomostraca, swarm in the water, on the mud and on the foliage of the water plants. 

 At such times trout feed mainly on them. They are eating the weed bare of the cling- 

 ing film of microscopic larvae of water-fleas, Cyclops and other fresh water ento7>iostraca. 



* * * Experiments made on trout showed that when fed upon worms only they grew 

 slowly, others fed upon minnows did better, but a single fish fed upon insects weighed 

 twice as much at the end of the experiment as a pair of those reared upon minnows 

 and worms respectively." 



This review brought up tne question of saimon fasting in fresh water, and Mr. 

 Cornish replied in a letter from which I make the following extract: 



"I am not quite sure whether there is not a period when salmon do fast, the result 

 of some sexual conditions. But this entomostraca probably forms a large part of the 



