ON THE MAMMALIAN NERVOUS SYSTEM. 



361 



amount ; in consequence of this, the comparison necessarily becomes less exact when 

 the method of averages is used. 



The following table gives this comparison in the case of six animals, four Cats and 

 two Monkeys. In three cases, (a), (b), (e), the effect was observed in one nerve and 

 each cortex alternately excited ; in the remaining three cases, (d), (e), (f), the 

 observations were made upon each nerve, one cortex only being exposed and 

 stimulated. 



From this table it is seen that, in the large majority of cases, unilaterality strictly 

 prevailed. The small average amount of the bilateral effects, dependent, moreover, 

 as it is upon a very few high readings, suggests that these results are due to that 

 constant source of error in experiments upon bilaterality of representation, viz., 

 hyperexcitability in other parts of the encephalon, produced by the operative 

 procedure. 



Examination of our records shows that when one corona is excited, and first one 

 nerve and then the other connected with the galvanometer, the following average 

 results were obtained : 



Corona radiata excited. 



Average of all effects . Nerve opposite side 26 (23 observations). 



Nerve same side 11 (20 observations). 



This average, however, is the result of all the observations made, some of them 

 being markedly bilateral in character. There are, however, no less than six cases 

 in which no effect at all was observed on the same side as the excited corona, 



HDCCCXCI. B. 3 A 



