520 NATURAL HISTORY OF AQUATIC ANIMALS. 



were taken within five or six inches of the surface, though they were frequently seen coming up 

 from as far below as they were visible. They were nearly white, with a pair of large, black eyes, 

 were, very active, moving continually, propelling themselves with a constant motion of the tail, 

 and swimming with the head up and the body depending at an inclination of about 50. They 

 seemed apprehensive of danger, and turned quickly from the dipper when it came near them, 

 occasionally escaping. They had no gregarious instinct whatever, and though occasionally taken 

 in pairs it was probably an accidental circumstance. 



"On April 14 we again visited the island and caught a number more of the young fish. 



"A few days later Mr. Clark and I visited the breeding-house of Mr. N. W. Clark, of Clarks- 

 tou. He had put down a large quantity of White-fish ova in November, and had taken the water 

 flowing over the eggs from a pond that had remained frozen over nearly all the winter. The 

 temperature of the water had remaiued at 34 or 35, and the young fish had begun to hatch out 

 on the 1st of April, and about the 9th or 10th were all out of the shell. This temperature is prob- 

 ably much the same as Detroit River at Ecorse, sixty-eight miles below Lake Huron, the current 

 flowing at the rate of two miles per hour. 



"The appearance of the umbilical sac in the specimens from both places made it evident that 

 they were of about the same age, and indicated the fact that in waters that are frozen over 

 throughout the winter the young White-fish escape from the egg about the first week of April. 



"The temperature of Lake Michigan, Huron, or Superior probably does not descend below 

 about 40 or 43 in ordinary winters, and the young fish would be likely to make their appearance 

 a week or two earlier. 



"The young fish lived in the glass jar of water two days, were then transferred to an eight- 

 ounce bottle, and carried over thirty hours by rail and steamer, and did not arrive at their desti- 

 nation, Waukegan, Illinois, until thirty-six hours after they left Ecorse, Michigan. They were all 

 in good condition, and were placed in a quart jar of fresh water. There were thirteen of them 

 altogether. 



"April 19. The young White-fish are very vigorous, and are in continual motion. The water 

 has been changed once. Although the yelk sac has not diminished, they act as if seeking food in 

 their movements around the jar. They open their mouths very wide. Occasionally they take in 

 dust masses and eject them again as if they were unpalatable. 



"April 21. Umbilical sac in one individual diminishing. 



"April 22. Umbilical sacs reducing rapidly. 



"April 23. Yelk sacs being rapidly absorbed. The membrane on the anterior part of dorsal 

 line is also slightly diminished. 



"April 24. The umbilical sacs becoming minute. The fin-membrane anterior to position of 

 dorsal becoming absorbed. At the center of the anterior ventral section of fin-membrane a slightly 

 opaque white spot is apparent. In front of the anus, and on lower half of caudal, are similar ones. 

 The color of the head is assuming a greenish tinge. 



"April 25. The globule in anterior part of yelk sac has become divided up into numerous 

 smaller globules, scattered like beads, or more like a row of bubbles, through the length of the sac. 

 When they open their mouths the gill-arches show quite distinctly. Excrement voided by some 

 of them. 



"April 28. Umbilical sac entirely absorbed. First dorsal fin becoming well defined. Pos- 

 terior section of dorsal membrane contracting. Furcation of caudal slightly indicated. 



"After an absence from home of six days, I returned on May G to find only one alive. A 



