600 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



tal, cystic, intestinal, and sudorific? To this list me may add 

 loss of control over all vasoconstrictors, since we have relaxa- 

 tion of the larger internal vascular trunks, central engorge- 

 ment, in virtue of the principle "vessels supplied with a mus- 

 cular coat and capillaries are mutually antagonistic in contrac- 

 tion and dilation" submitted in the earlier chapters and the 

 mechanism of which we can now understand. Both antag- 

 onistic conditions are expressed in another symptom of fear: 

 i.e., intense pallor, the lividity of Asiatic cholera and, indeed, 

 of the moribund. Truly instinctive, however, is the sudden cry 

 or scream brought on by unexpected pain: evidently the result 

 of an impulse to the posterior pituitary, since we again have a 

 series of muscular actions of the chest, glottis, etc., which are 

 necessary for the cry. Laughing, sneezing, coughing, and other 

 kindred acts are all manifestations of motor activity; and so is 

 vomiting the result of afferent and efferent vagal impulses, 

 again with muscular structures as the mechanical factors and 

 the posterior pituitary as inciting and governing organ. 



And a striking proof of this is furnished by the fact that 

 these manifestations of activity not only prevail in a frog de- 

 prived of its hemispheres, but that, if the animal is kept alive 

 and in good health, signs suggestive of intelligence appear. 

 "For days or even weeks after the operation," says Professor 

 Foster, "there may be no signs whatever of the working of any 

 volition; but, after the lapse of months, movements, previously 

 absent, of such a character as to suggest that they ought to be 

 called voluntary, may make their appearance. . . . Even 

 in their most complete development such movements do not 

 negate the view that the frog, in the absence of the cerebral 

 hemispheres, is wanting in what we ordinarily call a 'will/" Nor 

 need they, for these so-called involuntary, instinctive acts are 

 dominant even in vertebrates devoid of skull or brain: the 

 amphioxus, for example, down to which Andriezen traced the 

 structures which ultimately become the pituitary bodies. 



That the posterior pituitary is a discerning organ, and one, 

 at that, capable of simultaneously subserving many functions, 

 is sustained on all sides. Totally independent of the brain, 

 though its servant when need be, it appears to us as the undoubted 

 seat of the many centers i.e., for cardiac action, respiration, 



