THE SPASM-CENTER. THE SWEATING CENTER. 773 



due to nervous influences are a result of irritation of the vasodilators or of paralysis 

 of the vasoconstrictors. This is of great significance with respect to the interpreta- 

 tion of pathological phenomena. Emotional influences may also affect the vaso- 

 dilator center. Thus, the blush of shame, which may not only involve the face, 

 but may also extend to the entire skin, is probably due to irritation of the vaso- 

 dilator center. 



The vasodilator nerves obviously have a marked influence upon the bodily 

 temperature and upon that of individual portions of the body, as may be inferred 

 from what has been said with reference to the influence of the vasoconstrictors. 



It cannot be denied that both vascular nerve-centers represent important 

 regulators for the dissipation of heat through the vessels of the skin. Probably 

 they are maintained in activity by reflex influences through sensory nerves. 

 Derangement in the function of these centers may result in abnormal accumu- 

 lation of heat (as in the presence of fever) or in abnormal reduction of tempera- 

 ture. 



THE SPASM-CENTER. THE SWEATING CENTER. 



The medulla oblongata at its junction with the pons contains a center 

 irritation of which causes general convulsions. This can be excited 

 through sudden venosity of the blood (aspkyxial convulsions], also 

 through sudden anemia of the medulla oblongata either in consequence 

 of rapid hemorrhage or after momentary ligation of both carotid and 

 subclavian arteries (kemorrkagic or anemic convulsions] ; finally, also 

 through the action of sudden venous stasis as a result of constriction of 

 the veins passing from the head. Under all these conditions the irritation 

 of the center must be looked for in the sudden interruption of the normal 

 gaseous interchange If these influences operate gradually, death may 

 take place without the occurrence of convulsions, as the uninterrupted 

 gaseous interchange always associated with the onset of quiet death 

 shows. Also direct irritation by means of the application of chemical 

 substances, such as ammonium carbonate, potassium-salts, sodium- 

 salts, and others, is capable of rapidly exciting severe general convulsions. 

 Finally, it has long been known that intense direct mechanical irritation 

 of the medulla oblongata, as, for example, by sudden crushing, causes 

 general convulsions. 



As the convulsions occur only when the cerebrum is preserved, Bechterew 

 adopts the view that this portion of the nervous system contains only a motor 

 center, but no spasm-center, as with its destruction the power of locomotion 

 ceases. Convulsions occur on irritation of the area after the irritation is con- 

 veyed first to the cerebral cortex. 



According to Nothnagel the spasm-center in the rabbit extends above the ala 

 cinerea upward to the quadri geminate bodies. It is bounded laterally by the 

 locus coeruleus, together with the auditory tubercle, and internally by the eminen- 

 tia teres. The center is generally irritated in connection with extensive reflex 

 spasm. 



Numerous poisons, most heart-poisons, nicotin, picrotoxin, the salts of am- 

 monia and the compounds of barium cause death preceded by convulsions, as 

 they irritate the spasm-center. 



Pathological. Schroder van der Kolk pointed out that in cases of general 

 convulsions in epileptics the seat of irritation is situated within the medulla ob- 

 longata, the vessels of which he found repeatedly dilated and increased in 

 number. Under such conditions the medulla would be in a state of increased irrita- 

 bility. Now, it has been shown, in the discussion of the vasomotor centers, that 

 irritation of sensory nerves may cause both sudden contraction as well as dilatation 

 of the cerebral vessels. If this takes place in the vessels of the medulla, sudden 

 anemia or transitory hyperemia will develop in that structure. Both conditions 

 are capable, however, of irritating the medulla in such a manner that epileptiform 

 convulsions result. It is often the case in connection with general epileptic con- 

 vulsions that the nerve can- be distinctly demonstrated, irritation of which gives 



