10 THE TONER LECTURES. 



the loss of voluntary movement on the opposite side. But that 

 is not what we find. We see that the lesion which has destroyed 

 one-half of the brain may allow voluntary movement, while a 

 lesion which is not larger than a pea in any one part of the 

 brain can produce a loss of voluntary movement. Therefore 

 we are to admit that when the paralysis of movement comes in 

 connection with disease of one-half of the brain, it depends on 

 an influence starting from the place where the disease is acting 

 upon remote parts so as to produce a cessation of activity 

 there, or in other words a paralysis. 



The same reasoning may be applied in regard to perception 

 of sensation. Here also we find the same thing. I shall, there- 

 fore, not dwell on that point. We know a thousand cases of 

 disease occupying one-half of the brain that has not produced 

 the slightest alteration in the power of feeling. But, if it is so, 

 it remains to be explained how it is, that the two halves of the 

 brain come to be in some respects different, and that the phy- 

 siological and pathological study of the two halves of the brain 

 indicates great differences in this respect. If we pass in review 

 what is known, we find very great differences indeed. These dif- 

 ferences depend on the fact that, through the fault of our fathers 

 and mothers, the faults that weigh upon us, and have led us to 

 make use of only one-half of our body for certain acts, and one- 

 half of our brain for certain other acts also — we find that it is 

 owing to that defect in our education that one-half of our brain 

 is developed for certain things, while the other half of the bi-ain 

 is developed for other things. As regards what belongs to the 

 left side of the brain compared with the right side of the brain, 

 allow me to say the most important feature in its physiology or 

 pathology is what a French physician has discovered. It is, as 

 I have said already, that to that side of the brain belongs the 

 faculty of expressing ideas by speech Besides that mental 

 faculty of speech, the left side of the brain possesses, in a much 

 more marked degree than the right, the power of moving the 



