280 THE ADRENAL SYSTEM AND VASOMOTOR FUNCTIONS. 



may recall the fact that several toxic drugs reviewed in one of 

 our earlier chapters nicotine, for instance produced identical 

 effects. We have also seen that sweating is a marked symptom 

 of exophthalmic goiter during its cachectic stage, and, indeed, 

 of many diseases when marasmus prevails. In all of these 

 pallor of the surface and of the mucous membranes points to 

 the prevailing mechanical feature, i.e., engorgement of the 

 internal vascular trunks, and therefore to suprarenal insuffi- 

 ciency. In the sweat-glands proper the opposite condition to 

 that observed after the use of pilocarpine obtains: The func- 

 tional metabolism of the acini and of the tubular muscles is re- 

 duced; the canaliculi between their edges are unusually patent; 

 the entire structure of the organ is relaxed and allows the secretion 

 to exude more freely through its elements. 



How is this impairment of the sudoriparous functions 

 induced by suprarenal insufficiency? Section of the cervical 

 sympathetic in the horse is followed by profuse sweating on 

 the corresponding side of the head, owing to the relaxation 

 of the vessels: i.e., to loss of their tonic contraction. We also 

 know that section of the spinal cord below the medulla is 

 followed by the same loss of tonic vascular contraction through- 

 out the entire organism: experimental data which again refer 

 us to the medulla as the origin (apparent) of the impulse- 

 waves by means of which the sympathetic fibers govern the 

 vascular tone of the arteries and arterioles from which the 

 capillaries distributed to the sweat-glands are derived. We 

 are not only dealing, therefore, with a mechanical phenomenon 

 based upon reduced peripheral blood-pressure brought on by 

 the central engorgement, but with one in which the normal 

 functional activity of the centers is lowered just as it is low- 

 ered when the cord is cut below the medulla the scalpel 

 being replaced by a reduction of its blood-supply. We, there- 

 fore, have two interdependent causes for the relaxation of the 

 peripheral blood-channels, viz.: accumulation of the blood in 

 the central vascular trunks and loss of tonic contraction of 

 the peripheral vessels through the lowered potentiality of the 

 impulse-waves transmitted to the latter via their sympathetic 

 filaments. 



We have expressed the belief that there were but two 



