52 Roosevelt Wild Life Bulletin 



Kennedy House Camp, who has been on the lake for many seasons 

 and is very familiar with conditions. He says : " \\'e seemed to be 

 absolutely free of leeches at our place." My station 7 was located 

 at this camp and blood-sucking leeches were more plentiful there than 

 at any other point on the lake. At every visit during the summer 

 of 1919 leeches were foimd and the campers almost always had a 

 large number that they had captured for me. 



The evidence seems unequivocal, therefore, that there has been a 

 great decrease in the number of these leeches since the summer of 

 1919 during the progress of these freezing experiments. While it 

 cannot be said that the relation of cause and effect have been fully 

 established this probability seems sufficiently great to warrant the 

 recommendation of the method for the control of blood-sucking 

 leeches under conditions similar to those in Palisades Park: namely, 

 in bodies of water the level of which can be rapidly lowered, in which 

 there are shallow areas, and which are located in regions climatically 

 favorable. Just how far the method may be successfully applied 

 remains to be determined experimentally. 



REFERENCES TO LITERATURE 



BoiiN, J. 



1907. Les tropisms, le sensibilite differentielle et les association 

 chez le Branchellion de la torpille. C. R. Soc. Biol. 

 Paris, Vol. 63, pp. 545-548. 

 Bristol, C. L. 



1898. The Metamerism of Nephelis. Jour. Alorph., Vol. 15, 

 pp. 17-64. 

 Brooks, W. K. 



1882. Invertebrate Zoology. Pp. 1-392. Boston. 

 Brumpt, E. 



1901. Reproduction des Hirudinees. Mem. Zool. Soc. France, 

 Vol. 14, pp. 286-430. 

 Ebrard, E. 



1857. Novelle Alonographie des Sangsues Medicinalis. Pp. 

 I-XXH., 1-494; PI. 1-12. Paris. 

 Gee, W. 



1913. The Behavior of Leeches with Especial Reference to 

 its Modifiability. Univ. of California Pub. Zoology, 

 Vol. II, pp. 197-305. 

 Grimm, O. 



1883. Fishing and Hunting on Russian Waters. Inter. Fish- 



eries Exhibition, London, 1883. Pp. 1-55. St. Peters- 

 burg. 

 Moore, J. Percy. 



1901. Hirudinea of Illinois. Bull. Illinois State Lab. of Nat. 

 Hist., Vol. 5, pp. 479-547- 

 MoouiN, Tandon a. 



1846. Monographic des Hirudinees. Pp. 1-448; Atlas pp. 

 1-21, PI. 1-14. Paris. 



