I mills] FUNCTIONAT. DEVELOPMENT OF CEREBRAL CORTEX 9 



hut the fact that so strong a cuiTciit is necessmy to get the result in this 

 and other ver}' j'oung animals is suggestive. 



("ase VI. falls under the same remarks as the last, but seems to be 

 an instance in which the hind-leg centre is not clearly in advance of 

 the head. This is so rare that it is likel}- not actually so, but owing in 

 this case to some peculiar conditions of the moment. The very next 

 case (VII.) appears to bear out this view. It also seems to indicate that 

 the hind-leg centre is the tirst develoj^ed in this particidar animal. 



Case VIll. is especially instructive. There is clearh' a well-detined 

 cortical localization in this animal on the seventeenth day, and. notwith- 

 standing unfavourable circumstances, this localization is preserved. 



It is noteworthy that ablation of the area around the crucial sulcus 

 produces no paralysis, and, so far as can be readih" observed, no change 

 whatever in the movements of the animal, though it must be remembered 

 that a puppy's movements at this age are still but moderately well co- 

 ordinated ; nevertheless paralysis would undoubtedly be shown by the 

 leg bending under, etc., were it present even in moderate degree. 



Case IX. is apparently clearly in favour of the earlier functional 

 development of the medulla. 



Case X. s])eaks for an earlier development of the centre for the hind 

 limb. 



Case XI. is clearly one in which the centre for the hind-limb is best 

 developed. This case also points to an earlier development of the medulla. 



Case XII. is in favour of the earlier activity of the centre for the 

 hind-limb. 



Case XIII. I consider important, not onlj- because it illustrates per- 

 fectly the disastrous etfect of hamiorrhage, but because it seems to show 

 clearly that at an early period the centre for the hind-leg is the best 

 organized. 



Case XIY. is an example of my experience with St. Bernard puppies. 

 The motor cortical centres seem to develop later, which is in harmony 

 with the generally slower somatie and psychic development of the larger 

 breeds of dogs. 



Case XVI. is a])parently one in which the centre for the hind-leg 

 was not in advance of that for the fore-limb. 



General Conclusions. 



The following conclusions seem to be warrantly based on the fore- 

 going : 



There is no proper functional cortical develoi>ment in dogs before the 

 eyes open, i. e... before about the tenth to the thirteenth day of life. 



An advance in develo])ment is sometimes to be observed in a single 

 day. 



