FUNCTIONAL PARTS OF THE NERVOUS SYSTEM 73 



where the speech-center is located in children properly trained from the 

 first in ambidexterity. 



The olfactory center of the cortex in man is on the mesial surface in 

 front of and below the corpus callosum. It is situated in the uncinate 

 convolution, the anterior part of the gyrus fornicatus, and posteriorly 

 on the base of the frontal lobe. In those lower animals in which the 

 sense of smell is more developed than in man, there exist large special 

 olfactory lobes extending forward from the hemispheres. In many of 

 the brutes smell is the sense which, next to the kinesthesia, tells them 

 most about their environment. In man it is relatively unimportant, for 

 vision and hearing (owing to the evolution of speech) have superseded 

 this sense. There appears to be only a small amount of neural crossing 

 from one side to the other in the case of smell. 



The gustatory center also was thought by Terrier to be located in part 

 in the anterior portion of the gyrus fornicatus on the mesial cortex 

 (Bechterew), the first and second gyri. Smell and taste are closely 

 associated functionally in some cases (e. g., in eating), and it is likely that 

 this phenomenon may depend partly on the situation of the gustatory 

 center low down on the mesial surface of the temporal lobe close to (but 

 below) one of the centers of smell. Taste-buds, however, have recently 

 been found in the nose. In the anterior portion of this temporal area in 

 the monkey and cat stimulation produces movements of the lips and 

 tongue such as are naturally associated with tasting (Ferrier). Bechterew 

 obtained similar results in dogs from a corresponding spot on the cortex 

 of the brain, and in apes from the operculum. 



THE "ASSOCIATION-AREAS." The so-called association-areas of the 

 human cortex take up more than two-thirds of its surface. There are 

 three: the frontal area, the parietotemporal area, and the island of Eeil. 

 So far as direct experimental evidence goes, we know practically nothing 

 as to any special sensory or motor function of these regions, for they 

 seem to be inexcitable by the means which actively stimulate the motor 

 and sensory areas about them. Actual removal of these areas, under 

 the proper and extremely delicate conditions necessary, produces propor- 

 tional loss of mental faculty. At present, however, the particulars of 

 this loss cannot be given. Flechsig cites cases which show that loss in 

 the frontal areas is apt to be accompanied by a lessening of the inhibi- 

 tory habits of the individual, so that he becomes, like one of the lower 

 animals, deficient in cultural human control over the organic tenden- 

 cies. 



The name association-areas implies that they are the place where the 

 functions of the brain are associated by means of nerve-fibers and nerve- 

 cells. This may be seen, for example, in the loss of recognition exhibited 

 by animals that have had this area removed. Munk calls it "soul- 

 blindness." These "association-areas" are the portions of the cortex 

 about which least is known. Their function is largely psychological and 

 of a complex nature, if one may judge by the facts concerning these 

 regions so far discovered. 



