PHYSIOLOGY OF THE POSTERIOR PITUITARY. 505 



we must do, that in the intact animal the cortical area and 

 pyramidal tract play their part in carrying out voluntary 

 movements, their action is not of that simple character sup- 

 posed by the view referred to above. On the contrary, we are 

 driven to regard them rather as links important links, it is 

 true, but still links in a complex chain. As we have already 

 urged, we may probably speak of the changes taking place in 

 the pyramidal fibers as being, on the whole, of the nature of 

 efferent impulses; but we would go beyond ike evidence if we 

 concluded that they were identical with the ordinary efferent im- 

 pulses of motor nerves" All the features emphasized in 

 these quotations, especially in the last lines, appear to us to 

 isolate the hemispheres from the source of motor impulses per 

 se, and to confirm what experimental evidence obtained after 

 removal of the hemispheres had suggested: i.e., that the lower 

 cerebro-spinal structures constitute the executive intermediary 

 through which the cortical mandates are actively realized. 

 Yet, as is well known, these lower structures, in turn, manifest 

 their activity through the centers imbedded in them; what is 

 there to replace the energy in the form of motor impulses 

 which is erroneously supposed to be awakened by the "will" in 

 "certain cells of the cortical area"? 



Professor Foster partially answers this question when he 

 says: "The discussion in a previous section has shown that 

 much of the co-ordination of the body is carried out by the 

 middle portions of the brain, and on these the motor area 

 must .have its hold as on the spinal mechanisms. The details 

 of the nature of that hold are at present unknown to us." It 

 would appear from the facts reviewed that what might be 

 termed the central brain and the spinal cord constitute an 

 entity a mechanical entity, perhaps made up of working 

 centers, beginning with the olfactory bulb and the other nerv- 

 ous structures distributed to the nasal mucous membrane 

 anteriorly, and terminating with the end of the spinal cord: 

 i.e., the neural tract of lower forms. Motility, unconscious co- 

 ordination, and sensation but only, in the case of the latter, 

 to the extent of transmitting sensory impressions to their re- 



13 The italics are our own. 



