102 CONSCIOUSNESS AND SENSATION. 



each in the turtle, and in the bird the whole 

 hemisphere-vesicle converted into corpus striatum 

 (or, more correctly, corpus striatum and island 

 of Reil), with the exception of little more than a 

 membrane at the upper part. The hemisphere- 

 vesicle, therefore, appears to be a single organ 

 primarily divisible, as Reichert has beautifully 

 shown, into a root-part which includes corpus 

 striatum and island of Reil, and the " mantle " 

 which includes the remainder ; and I apprehend 

 that the mantle is only a imdtiplier of the function 

 of the root-part. 



If we now revert to one of the propositions 

 made at starting, and bear in recollection that 

 while there is every reason to believe that the 

 corpuscles of the hemispheres pass into the im- 

 pressed condition studied in nerves, there is no 

 vestige of evidence that they have any additional 

 active condition, it will become apparent that the 

 law of operation of the functions of the hemi- 

 spheres is that they are so connected with the 

 mind that the total amount of mental action at 

 one time is dependent on the total amount in the 

 Jiemispheres of that physical state which we call 

 the impressed condition. 



Consciousness and the impressed condition 

 of brain-substance go always together, but that 



