374 ANIMAL AGGREGATIONS 



Cohen, D. A. 1900. Casual observations of a colony of black-crowned night 



herons' colonial nesting habits. Condor 2:10-12. 

 CoHN, E. J. 191 7. Relation of H-ion concentration of sperm suspensions and 



their fertilizing power. Anal. Rec. 11:530. 

 . 1918. Studies in the physiology of spermatozoa. Biol. Bull. 34:168- 



218. 

 CoLTON, H. S. 1908. Some effects of environment on growth of Lymnaea. 



Proc. Acad. Nat. Sci. Phila. 60:410-48. 

 CoNKLiN, E. G. 1898. Environment and sexual dimorphism in Crcpidnla. 



Ibid. 1898: 435-44- 

 Conn, H. W. 1914. Social Heredity and Social Evolution. New York: Abingdon 



Press. 348 pp. 

 CoRNETZ, V. 191 2. L'illusion de I'entraide chez la fourmi. Rev. dcs Idccs 9: 292. 



9: 292. 

 Courtis, S. A. 1907. Response of toads to sound stimuli. Amer. Nat. 41: 



677-82. 

 Cox, Philip. 1889. A bird wave. Auk 6:241-4^. 

 Crabb, E. D. 1929. Growth of a pond snail, Lymnaea stagnalis, as indicated by 



increase in shell size. Biol. Bull. 56:41-64. 

 Craig, Wallace. 1908. The voices of pigeons regarded as a means of social 



control. Amer. Jour. Social. 14:86-100. 

 — . 191 1. Emotions in the pigeons. II. The mourning dove. Auk 28: 



398-408. 



1911a. Emotion in the pigeons. III. The passenger pigeon. Ibid. 



28:408-26. 



. 1914. Male doves reared in isolation. Jour. An. Bchav. 4:121-38. 



— — . 1916. Synchronism in the rhythmic activities of animals. Scioice 44: 



784-86. 

 Crampton, G. C. 191 2. Experiments performed upon Protozoa confined in 



capillary tubes. Arch. f. Protistcnkundc 27:9-15. 



. 1912a. Inhibition of cell division in Paramoecium. Science 35:634-35. 



Crozier, W. J. 1922. An observation on the "cluster-formation" of the sperms 



of Chiton. Amer. Nat. 56:478-80. 

 Cummins, Harold. 1920. The role of voice and coloration in spring migration 



and sex recognition in frogs. Jour. Exp. Zool. 30:325-43. 

 CuRRAN, H. R. 1925. The growth of bacteria. Thesis, Cornell University, 



Ithaca. 

 Cuthbertson, a. 1926. Studies on the Clyde crane flies. Ent. Monthly Mag. 



62:36-38,84-88. 

 Cutler, D. W., and L. M. Crump. 1923. The rate of reproduction in artificial 



cultures oi Colpiditim colpoda. I. Biochem. Jour. 17:174-86. 

 . 1923a. The rate of reproduction in artificial cultures of Colpidium 



colpoda. 11. Ibid. 17:875-86. 



