142 



ponred into jar No. 5, morning and evening, in the hopes that their 

 proper food was of this character. In jar No. 5, a variety of food 

 was provided, dry, fresh beef, milk, boiled potato, and bread. The 

 crumbs of bread and the scrapings from the beef were all that the 

 fish were seen to take into their mouths. They died, one after 

 another, very rapidly, and in a fcAV days all were dead." He fur- 

 ther remarks: "This difficulty of procuring a suitaljle food for the 

 young white-fish has been the experience of the few fish-culturists 

 who have hatched them." 



With the hope of ascertaining the natural food of these fishes, 

 a few specimens, representing young captured in the Detroit River, 

 and others from the hatchery, were submitted by Mr. Milner to Mr. 

 S. A. Briggs, a microscopist, of Chicago. Four examples were ex- 

 amined by Mr. Briggs, two from each of the above situations. 

 Those from the hatchery contained nothing whatever, while those 

 from Detroit Eiver contained numerous specimens of Diatomaceae ; 

 viz. Frag'daria capucina and Stcphanodiscus niaganf. The only fact 

 at that time known would consequently indicate that the earliest 

 food of the species consisted of Diatomacese. 



The white-fish, as is well known, lays its eggs in the open lake 

 in autumn, the young not appearing until early in the (oUowing 

 spring. At this cold and stormy season in the exposed situations 

 where they are to be sought, it is practically impossible to find the 

 young fish; a fact which rendered the study of their earliest food a 

 subject of unusual difficulty. There seemed, in fact, no practicable 

 way to reach satisfactory conclusions upon it except by experiment 

 upon individuals artitically hatched. 



In December, 1880, I made an arrangement, through the kind- 

 ness of Prof. Baird, of the Smithsonian Institution, with Mr. V. N. 

 Clark, superintendent of the U. S. fish hatchery at Northville. 

 Mich., lor a supply of young Avhite-fish to be sent me at intervals 

 from the hatchery under his control. The specimens furnished were 

 taken from two lots. The hshes of one lot, hitched January 18. 

 were kept in a tank in the haichery, where they were supplied with 

 water from a spring, which had been cooleil by exposure to the air 

 in artificial ponds before entering the hatchery, in order to retard 

 the development of the fry. The ordinary lange of temperature in 

 the tank was from thirty-five to thirty-nine degrees. These tishes 

 were fed daily with a paste made by grinding small amphipod 

 crustaceans (Gammarus) in a mortar. 



The second lot, hatched January '20, was kept, unfed, in a per- 

 forated tin box. in a rivulet flowing from a spring, about sixty feet 

 from its source. The water had a uniform temperature of forty- 

 seven degrees. 



Those in the spring being in warmer water than the others, de- 

 veloped much more rapidly, and it was believed that the character 

 and source of this water was such as to furnish them at least a 

 small supply of such food as young fishes are accustomed to appro- 

 priate. 



Ninety specimens were received from the hatchery February 9, at 

 which time they were three weeks old. They were thirteen mm. 

 (half an inch) in length by one in depth. The egg-sac was but 



