THE LOWER BRAIN. 



485 



Flourens's noeud vital, therefore, is no more the respiratory 

 center than the area traversed by the current can be called 

 an "inhibitory" area. We are simply dealing with the results 

 of two morbid factors: overstimulation (Weber) and inter- 

 ruption (Flourens) of physiological and therefore functional 

 impulses transmitted through the medulla and the cord. 



In the fifth chapter reference was made to the fact that 

 the posterior pituitary lobe alone, as shown by Howell, con- 

 tained an active principle. This lobe, the "infundibular," has 

 long been termed the "neural" portion of the whole organ, 

 and appears to us to anatomically present features that sug- 

 gest a direct connection between it and the cerebro-spinal 

 centers. Hence the use of the words "physiological impulses 

 transmitted through the medulla and the cord." The question 

 becomes all the more worthy of a searching inquiry inasmuch 

 as a casual examination of the mutual relations, anatomical 

 and physiological, of the cerebral structures traversed by the 

 current in the experiment of the Weber brothers suffices to 

 show that the elements thus submitted to excessive stimulation 

 coincide with those which would normally fall under the in- 

 fluence of the posterior pituitary body. 



The physiological characteristics of the parts influenced 

 by the current must first be ascertained. In the frog, the dis- 

 tance between the nose and the medulla being very short, a 

 current would implicate all elements in its direct path, con- 

 sidering the character of the structures traversed. In this 

 animal, the lizard, etc., the nasal nervous terminals, the tissues 

 about the floor of the median ventricle and the habendula, 

 appear to us as the paths that would be involved. In man the 

 distance between the olfactory area or the nasal subdivisions 

 of the fifth pair and the medulla is also relatively limited, and 

 the intervening structures are of such a nature as to also allow 

 the current to pass uninterruptedly in a straight path. But the 

 floor of the median or third ventricle, which in its anterior 

 portion overlies the base of the skull and is very thin, becomes 

 what appears to us the inevitable path of free conduction, owing 

 to this proximity of the olfactory bulb and the trigeminal nasal 

 terminals, to the medullary centers. Of special interest to us, 

 however, is the fact that in man (and to a great extent in the 



