XX Journal of Comparative Neurology. 



all lower vertebrates and in some mammals — cat, rat, mouse, rabbit — 

 each glomerule receives the protoplasmic process from a single mitral 

 cell, while in the dog five or six mitral cells effect connections with the 

 same glomerule, thus putting each olfactory fibre into relation with a 

 larger number of cortical cells. Examination of the olfactory lobe of 

 the still-born child with the silver method shows the usual mammalian 

 type with the following exceptions : (i) the mitral cells are more ir- 

 regularly arranged than in other mammals, lying often in the glomeru- 

 lar layer or even among the peripheral nerve fibres; (2) the protoplas- 

 mic processes of the mitral cells occasionally branch, communicating 

 with more than one glomerule as in the lower types ; (3) most of the 

 glomerules receive the protoplasmic process of but a single mitral cell, 

 though sometimes two to four mitral cells are related to the same glom- 

 erule as in the dog. c. j. h. 



The Relation of Sensory and Motor Areas of the Cortex. 



The evidence has accumulated in abundance to show that the sep- 

 aration of motor and sensory areas is arbitrary and untrue to the actual 

 facts. The ease with which motor disturbance can be demonstrated 

 may very well account for the pre-eminence given to the location of 

 motor functions. Munk has shown in a series of brilliant experiments 

 that even in the visual area the various portions may produce complex 

 motor responses in the form of coordinated eye movements. The same 

 author has shown that the various cortical motor areas are not exclu- 

 sively so but that approximately the same regions have a sensory func- 

 tion also. But for our present purpose it is of importance to show that 

 the same generalization holds good for the human brain. From the 

 vast material at our disposal it is only necessary to call attention to the 

 selected cases described by by Dr. C. L. Dana.i The analysis of these 

 cases shows, as the author states, that it is the power of localization which 

 is first to be disturbed in case of injury to the cortex, next tactile anaes- 

 thesia then analgesia, then simple muscular anaesthesia and, finally, loss 

 of temperature sense. Now the higher forms of coordinated sensations 

 owe their existence as much to vestiges of earlier sense presentations as 

 to the actual sense content. This is especially true of localization 

 and muscular sense. It appears then that one of the most constant of 

 the results of cerebral injury is the impairment of the vestiges or the 

 interruption of the paths connecting with the store-house of such im- 

 pressions. It is a well-known fact that the extent to which vestigial 



^Jeurn. Nerv. and Ment. Dis., Dec, 1894. 



