§2 WESLEY MILLS ON 



The "opening of the eyes " is really a separation of the lids, which are practically one 

 at birth, by a process of growth and absorption alongthe line of their future edges. These 

 processes take a few days for completion even after there is an obvious opening between the 

 lids ; and it is very doubtful if the animal sees at all in the proper sense of the word until 

 the lids are completely separated, if even then ; so that the eyes being open is in itself no 

 guarantee that the animal sees, or at all events more than light and shadows. 



The slowness of reflex winking to appear in puppies is surprising, the more so as 

 mature dogs wink very readily when any object is brought near or moved before the eye. 



Quite otherwise is it with mature birds, and it is almost impossible to get the young to 

 wink, even on touching the lids in some cases I have found. 



In this and a former litter of St. Bernards, the eyes began to open on the 11th day, and 

 in a litter of Bedlingtou terriers on the same day or perhaps a little earlier. One writer 

 states that the eyes of dogs open on the 8th day. I have never seen this and do not believe 

 it holds for any pure-bred dogs at all events. 



But individual difterences show to the extent of at least twelve hours. 



Hearliuj. — It is very easy to be deceived in this on account of motor eftects resulting 

 from concussion, or from contact of blasts of air with the skin. I think, however, my 

 experiments will be deemed conclusive and the record of the development of this sense very 

 full. 



There comes a time as I have noted when the young dog is more affected by sounds 

 than an older one, owing to the less perfect development of his cerebral cortex, which part 

 of the brain is associated with all higher jjsychic manifestations, with voluntary movements, 

 inhibitions, etc. To this the lack of experience is to be added, for till the dog has learned 

 better, noises of all kinds are excitements which may have unpleasant associations or the 

 reverse. The mature dog has embedded in his nervous system and psychic nature a series 

 of connections which without any reasoning answer to warn him or the reverse or are per- 

 fectly indifferent. 



However, new and mysterious sounds may alarm a mature dog more than a puppy. 



The lower animals are more sensitive to concussions than man as shown by their 

 behaviour prior to earthquakes when there are slight oscillations of the earth, wholly 

 unpereeived by man, yet causing alarm to the domestic animals. 



I have noticed that puppies are very early stimulated by concussions, but regret that I 

 have not exact observations with tixed dates to report. 



One of the earliest indications of hearing is reflex movement of the ears. These are 

 quite distinct, of course, from the voluntary movements often seen in dogs and other 

 animals. But similar though less marked movements of the external ears may lie observed 

 in man also, as any one may prove by asking an individual to listen and determine the loca- 

 tion of a tuning fork sounded behind him. These I have for many years been accustomed 

 to demonstrate to my classes in physiology, though I have not noticed that they are referred 

 to in books. There seems to be no relation between the extent of the reflex and the volun- 

 tary movements of the ears, of which some people are capable. When at concerts I have 

 sometimes observed them in great numbers and variety. 



Another matter that seems to have received scant attention if I may judge from the 

 absence of printed references, is the condition ot the ears in puppies up to a certain date. 

 At birth the external ear is turned back and its internal aspect strikes one by its relatively 



