802 PERIODIC FUNCTIONS IN MAMMALS 



cerebri (the master gland) and that the amount of light per day does 

 not influence this gland. 



REFERENCES 



Moore, C. R., G. F. Simmons, L. J. Wells, M. Zalesky, and W. O. Nelson. 



1934. On the control of reproductive activity in an annual-breeding mammal 



(Citellus tridecemlineatus) . Auat. Record, 60, 279-89, 

 Simmons, G. F. 1934. A study of sexual periodicity and its control in the 



female rodent Citellus. Dissertation, The University of Chicago Library, 



Chicago. 

 Wells, L. J. 1935. Seasonal sexual rhythm and its experimental modification in 



the male of the thirteen-lined ground squirrel {Citellus tridecemlineatus). 



Anat. Record, 62, 409-47. 

 . 1938. Gonadotropic potency of the hypophysis in a wild male rodent 



with annual rut. Endocrinology , 22, 588-94. 

 Wells, L. J., and M. Zalesky. 1940. Effects of low environmental temperature 



on the reproductive organs of male mammals with annual aspermia. Am. J. 



Anat., 66, 429-47. 

 Zalesky, M. 1934. A study of the seasonal changes in the adrenal gland of the 



thirteen-lined ground squirrel (Citellus tridecemlineatus), with particular 



reference to its sexual cycle. Anat. Record, 60, 291-321. 

 . 1935. A study of the seasonal changes in the thyroid gland of the 



thirteen-lined ground squirrel (Citellus tridecemlineatus), with particular 



reference to its sexual cycle. Anal. Record, 62, 109-37. 

 Zalesky, M., and L. J. Wells. 1940. Effects of low environmental temperature 



on the thyroid and adrenal glands of the ground squirrel, Citellus tridecemli- 

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