194 'Journal of Comparative Neurology and Psychology. 



The Sense of Vision in the Dancing Mouse. By Robert M. Yerkes. Harvard 



University. 



That brightness vision is fairly well developed in the dancer is shown by its 

 ability to discriminate blacks, greys and whites. Color vision is extremely poor. 

 There is some indication of the discrimination of red and green and of red and blue, 

 but none whatever of blue and green. All my experimental tests as well as my 

 observations of the habits of the mouse support the conclusion that such visual 

 guidance as is received results from stimulation by brightness differences. There 

 are many reasons for believing that the red end of the spectrum is much lower in 

 brightness value for the mouse than for man. The general behavior of the dancer 

 and the results of form, brightness and color tests show that vision is not very impor- 

 tant in the hfe of the animal. 



The Breeding Habits of the Florida Alligator. By Albert M. Reese, Syracuse 



University. 



The habits of the alligator were studied during parts of three summers in the 

 Everglades, in the swamps of central Florida, and in the Okefenokee Swamp. 

 The time of laying is the month of June, usually during the second and third weeks. 

 The nests, which are built on the bank near the caves of the alligators, vary con- 

 siderably in size, and consist of a very compact mass of damp, decaying vegetation. 

 They probably serve more as a means of keeping the eggs moist and at a constant 

 temperature than as a means of heating them. The average number of eggs in a 

 single nest is about thirty, forty-eight being the greatest number found in one nest. 

 1 he eggs are so closely packed in the nest that it seems hardly possible that the 

 young alligators, on hatching, should be able to dig their way out; it is possible that 

 the female who laid the eggs may hear the noise made by the young before hatching 

 and may dig them out of the nest before they suffocate. The period of incubation 

 is probat)ly about eight weeks, and sometimes is found to have begun before the 

 eggs are laid, so that eggs taken directly from the oviducts may contain well 

 advanced embryos. There is considerable variation in the size of the eggs, the 

 variation in long diameter being greater than that in short diameter. The average 

 long diameter of the four hundred eggs measured was 73.742 mm. The average 

 short diameter was 42.588 mm. 



Analysis of the Cyclical Instincts of Birds. By Francis H. Herrick, Western _ 

 Reserve University. 



The behavior of wild birds is primarily determined by a number of commanding 

 instincts of ancient origin. These cardinal instincts are of two kinds, namely: (l) 

 continuous instincts, which are needed for the preservation of the individual, such 

 as preying, fear, concealment and flight, and (2) cyclical instincts, which are 

 necessary for the maintenance of the race. By cyclical instincts we mean those 

 discontinuous, recurrent impulses which attend the reproductive cycle, and which 

 may be described as parental instincts. 



The cyclical or parental instincts as a rule recur with almost clock-like precision, 

 in spring or summer, with repetitions within the breeding season in certain species. 

 They are modified by the continuous instincts, such as fear, and the instinctive 

 behavior as a whole is liable to modification at every point by intelligence. Neglect- 

 ing such changes for the present, we will briefly analyze the cyclical instincts, 

 reserving details and tabular statements for a fuller presentation. 



