202 BIOLOGICAL RELATIONS OF AQUATIC FORMS 



Spangler, A. M., "The Decrease of Food Fishes in American Waters 

 and Some of the Causes." Bulletin U. S. Fish Commission, 1893, 

 pp. 21-35. 



Adams, Cyrus C., "The Sargasso Sea." Harpers' 1 Magazine, Novem- 

 ber, 1907. 



Wieland, Geo., "Conservation of the Marine Vertebrates." Popular 

 Science Monthly, May, 1908. 



Herdman, W. A., "Our Food from the Waters." Science, Novem- 

 ber 26, 1909. 



Peck, Jas. I., "The Sources of Marine Food." Bulletin U. S. Fish 

 Commission, 1895, pp. 351-368, many plates. (For the teacher.) 



Osborn, Herbert, " Needed : A System of Aquatic Farming." Popular 

 Science Monthly, July, 1908. 



Forbes, S. A., "The Lake as a Microcosm." Bulletin Peoria (111.) 

 Science Association, 1887. 



Shannon, H. J., "The Microscopic Animals of the Sea." Harpers' 

 Magazine, June, 1910. 



Johnston, James, Conditions of Life in the Sea. 



Pratt, D. L., "Farming the Seas." Outing Magazine, September, 

 1908. 



Pahlow, G., "The Wonders of the Deep." Cosmopolitan Magazine, 

 July, 1908. 



PROBLEM XXXVI (Optional) 



The artificial propagation of fisfos. 



Observations. 1. Schools in the neighborhood of state or govern- 

 ment fish hatcheries l may well visit them and watch the artificial methods 

 of raising fishes. If possible watch the "stripping" of the females for 

 roe (eggs) and the males for milt (sperm). Which is the larger, roe or 

 milt ? Which is the more active ? Why ? 



2. Note that the roe is squeezed out into a moist bucket, and the 

 milt is immediately -poured over it and the eggs gently stirred about. 

 Why? 



3. Several changes of water are now poured over the eggs and they 

 are then set aside to develop. 



Conclusions. 1. What is meant by the term "artificial fertiliza- 

 tion" ? 



1 In lieu of such hatcheries, study Figures of the process, for salmon or 

 trout. See a Manual of Fish Culture, Department of U. S. Fish Commission 

 for 1898, Plates 16, 28, 34, 53, especially for salmon and trout. 



