^^^^] Gee: Behavior of Leeches 305 



UeSKULL, J. VON 



1905. Studien fiber den Tonus, III. Die Blutegel. Zeitschr. f. Biol., 



46, 372-402, 17 figs, in text. 

 1909. Umwelt und Innenwelt der Tiere. (Berlin, Springer), 159 pp. 

 Valmont de Bomare, J. C. 



1776. Article sangsue. Diction. d'Histoire Nat. (Lvon, 3e edition), 

 8, p. 63. 

 Verrill, a. E. 



1873. Synopsis of the North American fresh-water leeches. U. S. 

 Fish Com. Rep., 1872-1873, 666-689. 

 VlTET, L. 



1809. Traite de la sangsue medicinale. (Paris), 1 pi. 

 Wagner, G. 



1905. On some movements and reactions of Hydra. Quart. Journ. 



Micr. Sei., 46, 585-622, 6 figs, in text. 

 Whitman, C. O. 



1878. The embryology of Clepsine. Quart. Journ. Micr. Sei., 18, 215- 



315, 4 pis. 

 1886. The leeches of Japan. Ibid., 26, 317-416, 5 pis. 

 1891. Spermatophores as a means of hypodermic impregnation. Journ. 



Morph., 4, 361-495, 1 pi. 

 1899. Animal behavior. Biol. Lect. Marine Biol. Lab., Woods Holl, 



1898, pp. 285-338. 

 Yerkes, Ada W. 



1906. Modifiability of behavior in Hydroides dianthus V. Journ. 



Comp. Neur. Psychol., 16, 441-449, 1 fig. in text. 

 Yekkes, R. M. 



1912. The intelligence of earthworms. Joiirn. Anim. Behav., 5, 332- 

 352, 5 figs, in text. 

 Yoakum, C. S. 



1909. An experimental study oi. fatigue. Psychol. Monographs, 12. 

 vi + 131. 



