THE HARVARD LABORATORY OF ANIMAL PSYCHOLOGY 177 



room of the investigator or to such quarters as the special con- 

 ditions of the experiment demand. 



' The vivarium-room contains, in addition to provisions for 

 water-inhabiting animals, cages of a variety of forms and sizes. 

 The largest of these cages, six and a half feet high, six feet wide, 

 and four feet deep, may be used for birds, monkeys, or any of 

 the medium-sized mammals. Cages for rabbits, guinea-pigs, 

 and other small animals are arranged in frames which support 

 four double compartments. Similarly, small cages suitable for 

 mice, rats, and other small rodents are in supporting frames 

 which carry four of the double cages, each of which is removable 

 and may be carried to the experimenting-room at the convenience 

 of the experimenter. 



' Ina large unheated room above the main laboratory are tanks 

 for amphibians and reptiles. These tanks, since they can be 

 kept at a low temperature during the winter, are very convenient 

 and useful for frogs, tortoises, and similar hibernating animals." 



Work progressed satisfactorily in these quarters until the 

 spring of 1913, when the introduction of experimental work in 

 Educational Psychology, rendered desirable a redistribution of 

 space. During the summer of 1913, the unfinished fourth floor 

 of Emerson Hall previously referred to was developed, in accord- 

 ance with plans prepared by the writer, as a laboratory of animal 

 psychology. The floor plan of this new laboratory is presented 

 in the accompanying figure 1. 



Ten rooms, in addition to an office for the director of the work, 

 are now at the service of students of animal psychology. Of 

 these rooms, several were especially planned and have been at 

 least partially equipped for definite lines of inquiry. Thus 

 rooms 40 and 41 have been built about the Yerkes and Watson 

 apparatus for the study of the several aspects of vision in animals. 

 Preliminary studies of vision by simpler rough and ready methods 

 are conducted in other rooms of the laboratory, or at the Field 

 Station described below, and the more elaborate apparatus is 

 used only for accurate and thorough-going investigations. By 

 means of our varied visual equipment, it is possible to study color, 

 intensity, size, form, and distance perception with a degree of 

 exactitude which heretofore has been exceptional in connection 

 with studies of animal behavior. 



Room 42 is equipped with the Watson circular maze and the 



