Trophic, Secretory and Vasomotor Disturbances. 435 



thin bands of fibrous connective tissue. To what degree this 

 atrophy may be due simply to the motor inactivity or is dependent 

 upon a loss of proper nutritive influences as the principal factor is 

 not certain. In simple disuse of muscles, as that obtaining in case 

 of disease of the joints and bones or artificial fixation, atrophy may 

 not appear for a long time, and the structure and electrical irrita- 

 bility remain unchanged, because the motionless muscle is still in 

 connection with its unaltered ganglion cell, performs other functions 

 as heat production and metabolism, and continues to receive impulses 

 of various kinds. In a neuropathic paralysis, however, the muscle 

 no longer receives stimuli from the nerves and its metabolism no 

 longer is as active; and atrophy may set in as early as within the 

 first week after the nerve lesion, and may be so marked that in the 

 course of a month tlie muscle may be reduced to half its former 

 thickness. From these considerations it is evident that not mere 

 inactivity alone, but the loss of some special trophic relation between 

 the nerves and muscle, determine the issue. 



The most common example of such neuropathic atrn]i]iy is ^^een 

 in the shrinkage of the posterior crico-arytenoid muscle in laryngeal 

 hemiplegia (laryngeal wheezing in the horse). 



(For details v. Friedberger-Frohner. Veterinary Pathology, Amer. Ed.. 

 W. T. Keener & Co., Chicago; Dexler, Die Ncrvenkrankheiten des Pfcrdes, 

 1S99 (Denticke's Verl.) ; Thomassen. Moiiafsheft f. praht. Tierhcilkunde.) 



In the same way in case of disease or loss of continuity of the 

 nerves nutritional disturbances develop in the bones (rarefaction, 

 atrophv), the salivary glands and testicles (diminution in size, de- 

 generation of the parenchymatous cells). The effect of castration 

 upon the development of the body and the change of physical habit 

 is presumably also to be attributed to some trophic influence of the 

 nervous system. 



Secretory disturbances resulting from nervous lesions conform 

 closely to the known physiology of glandular activity. It is well 

 known that by direct or indirect stimulation of the secretory nerves 

 of the salivary glands (facial nerve, gustatory nerve, trigeminus 

 and branch of glosso-pharyngeal : stimulation by digitalin, pilocarpin, 

 or inflammation) an increased, sometimes permanently increased, 

 secretion of saliva results. Similarly a flow of tears is induced by 

 stimulation of the lachrymal nerve, cervical sympathetic, trigeminus, 

 and, too, reflexly by irritation of the nasal mucous membrane. 



Vasomotor disturbances (angioneuroses) manifest themselves by 

 abnormal dilatation or constriction of the vessels, the former deter- 



