DUAL CHARACTER OP THE BRAIN. H 



the right side of the brain that is affected, showing the connec- 

 tion between the development of one-half of the brain in the use 

 of one arm, and the development of that same half of the brain 

 in the faculty of expressing ideas by speech. There is, there- 

 fore, a connection between these two things, and on this point 

 I shall dwell a little more in a moment. There is primitively a 

 difference between the two brains, and Professor Gratiolet has 

 discovered in children that the second convolution — the convo- 

 lution of the left side of the brain — is developed quicker than 

 the convolution of the right side. This may be in a measure 

 owing to hereditary traits ; but at any rate, as there is an evidence 

 that there is a natural tendenc}^ to make use of the right arm, 

 it is certain that a part of that ability of development on the 

 left side is due to something natural — that something natural 

 will be found, if it is examined, in the greater supply of blood 

 to that part. Even parrots and birds show something very 

 interesting as regards right-handedness. Parrots perch only 

 on the right leg, or mostly only on the right leg. Very few 

 parrots out of twenty taken at random, perch on the left leg, 

 according to what Dr. William Ogle ascertained after having 

 examined a great number of them. Parrots, of course, are 

 known to have something like sj^eech — a parrot's speech, of 

 course. It is perfectly well known that the mechanical parts 

 of speech belong to them, and it is remarkable that their left 

 brain receives also more blood by far than their right brain. 

 There is therefore a relation between all these things in tlie 

 development of the right side of the limbs and the amount of 

 blood received by the left side of the brain. There is another 

 point of importance. Prof. Broadbent and others have found 

 that in the left side of the brain the mass of gray matter is 

 greater, and there are more convolutions than in the right side 

 of the brain. 



Now we come to four points of great importance in this 

 lecture. They are the vital points, I may say, in the argument 



