28 



BIOLOGY 



nos of the common strain, the following maximum weights for 

 each sex at known ages have been observed by King (MS '15). 



TABLE 9 

 Body weight in grams 



10. Behavior, a) The normal activities of the rat under 

 natural conditions have been studied and described by a num- 

 ber of observers (see references). 



b) As the albino rat is easily tamed and responds readily to 

 training it has already been used for a number of studies in which 

 behavior tests have been employed. Studies have been made 

 for example on imitation, temperament, the influence of prac- 

 tice, retentiveness, the role of the several organs of sense and 

 the relation of the learning rate to age and to the relative brain 

 weight (see references). 



biology: references 



Life history. Donaldson, '08. King, '13. Kirkham, '10. Kirkham and 

 Burr, '13. McCoy, '09. Slonaker, '07, '12. Stewart, 1898. Watson, '03. 



Span of life. Donaldson, '08. Slonaker, '12, '12 a. 



Puberty, Ovulation, Menopause. Hewer, '14. Kirkham and Burr, '13. 

 Sobotta and Burckhard, '10. 



Period of gestation. King, '13. 



Superfecundation. King, '13. 



Fecundity and weight at birth. Crampe, '84. King, '15. King and Stotsen- 

 burg. '15. Kolazy, 1871. Lloyd, '09 a. Pearson, '10. Sobotta and Burckhard, 

 '10. Watson, '06 a. 



Recognition of sex. Jackson, '12. 



Sex ratio. Cuenot, 1899. King, '11 a, 11 b. King and Stotsenburg, '15. 



Body weight according to sex. King and Stotsenburg, '15. 



Behavior, a) Under natural conditions. Advisory Committee, '12. Bech- 

 stein, 1801. Bell, 1837-1874. Buckland, 1859. Buff on, 1749-1789. Dehne, 

 1855. Fisher, 1872. Hewett, '04. Kolazy, 1871. Lambert, '10. Lantz, '10. 

 Manouvrier, '05. Mitchell, '11. b) Under experimental conditions. Adams, 

 '13. Basset, '14. Berry, '06. Carr and Watson, '08. Cesana, '10. Hubbert, 

 '14, '15. Hunter, '12, '13. Lashley, '12. Richardson, '09. Small, 1899, 1900, 

 '01. Szymanski, '14. Ulrich, '13. Vincent, '12, '13, '15, '15 a, '15 b. Watson, J. 

 B., '03, '07, '13, '14. 



