62 WESLEY MILLS ON THE PSYCHIC DEVELOPMENT OF YOUNG ANIMALS. 



that experience even in tlie earliest days is not lost on them. In other words the environ- 

 ment does and must act on the nervous system with results that manifest themselves if in 

 no more definite way at least in this : that new experiences (stimuli) cause comfort or discom- 

 fort as evidenced by quiescence or wriggling, cries, etc. 



Co-ordinated muscular movements appear in greatest perfection in a certain order, viz., 

 mouth and head parts, fore-limbs, hind-limbs, tail, etc, 



These seem to be related to the order of development of the centres of the cerebral cortex. 

 The epochs most ditferentiated from each other in the psychic and somatic life of the 

 dog are (1) That prior to the opening of the eyes and (2) That subsequent to this event. 



The former suggests intra-uterine life by its negative character ; and is well marked ofi 

 from the period that follows the more numerous avenues of knowledge existing, and their 

 utilization and in other respects not well understood, of the latter period. In other words 

 the animal after this period can come more fully in contact with environment with corres- 

 ponding results in its development. It seems besides more impelled to do so ; there is 

 more vim in its whole nature. A transition period between the time when the eyes and ears 

 begin to open and when the animal actually sees objects and hear sounds may also be 

 recognized. 



The era of most rapid and most important development is subsequent to the period 

 when seeing and hearing are established — when the animal is in possession of all its senses, 

 etc. This extends between about the 20th and the 45th day approximately. 



Suggestive action beginning perhaps with the first manifestations of the play instinct 

 has, especially as time passes, a very important share in determining the direction of de- 

 velopment, and what manner of dog the individual becomes. It is education in the more 

 limited sense. 



The order of development of the senses and co-ordinated movements as well as reflexes, 

 and the manifestation and perfecting of instincts have a distinct relation to the needs as well 

 as the general development of the animal, e.g. smell is always more important to the dog 

 than any of his other senses, and it is early developed. The same remark applies to the 

 movements of the jaws and the limbs over those of other parts. 



The detailed study of the development of the dog as recorded in the foregoing pages 

 illustrates how dependent all subsequent advancement is on the early and full development 

 of the senses and co-ordinated movements. They bring the nervous centres into contact so 

 to speak with the environment. 



The same is illustrated in the study of the human infant ; but in the case of the dog the 

 investigation is not surrounded by the same complications or at all events prejudices. 



Although it is not possible as yet to determine the physical and psychic correlations 

 down to the minutest details, from what has been accomplished, it seems reasonable to hope 

 that a complete correlation may be ultimately established. 



The first sixty days of a dog's existence are of so much more consequence than any later 

 period, that the writer has decided to limit this paper to this period — within which almost 

 all important features in development appear. 



