PHRENOLOGY. 213 



662. We have added this long extract, from one of the 

 highest physiological authorities of the age, to that of Dr. 

 Roget, for the purpose of showing those into whose hands 

 this volume may happen to fall, that there is still a doubt 

 among the most competent judges in Europe, not only 

 whether phrenology is likely to be of any practical utility 

 to man, but even whether it has any foundation in nature. 

 At the same time, as it is acknowledged by the advocates 

 of its doctrines themselves, that it must stand or fall on 

 the facts which can be adduced for or against it, we can 

 see no objection to their accumulation, provided, in the 

 meantime, the public curiosity can be so suspended as to 

 prevent the waste of too much time in studying it, or the 

 adoption of a system which does not at present appear to 

 be of any great practical use to the rising generation, 

 whatever it may ultimately become. 



663 Double Organs of the Mammalia. In man, ^as 

 well as in all the other vertebrated animals, every organ 

 subservient to the sensorial functions, and most of those 

 concerned in voluntary action, are double ; that is, there 

 is a symmetrical organ on each side, whose powers and 

 functions are exactly alike. Thus, we have two eyes, 

 two ears, two arms, legs, &c. The same law holds 

 with respect to the brain, this part, as we have shown, 

 being divided into two equal parts, called the right and 

 left hemispheres ; so that, in fact, we have two brains, 

 and a double set of nerves, as well as double eyes and 

 ears. 



664. In the sensorial functions, these two parts consti- 

 tute, in action, only a single organ of sensation ; thus the 

 action of the two eyes convey to the mind only a single 

 impression, and of the two ears only a single sound. 

 This effect is produced by a free communication which 

 exists between the two divisions of the brain, by means 

 of medullary substances, called the commissures of the 

 brain, and which pass directly from one hemisphere to 

 the other. The principal commissure is the corpus col- 

 losum, shown at g, Fig. 120. In the functions of most 



What is said of the doable organs of the sensorial and muscular pow- 

 ers ? In sensorial action, is the effect double or single ? 



