Thermic Influences. 47 



casionally a sudden chilling of the feet brings on directly a reflex 

 sneezing and nasal catarrh. Rossbach has observed in experiments 

 upon cats that by applying cold compresses over the abdomen vas- 

 cular constriction passing over into vascular dilatation develops in 

 the mucous membrane of the respiratory passages. There usu- 

 ally succeeds upon the vascular constriction a relaxation of the 

 vessel walls with which is associated a marked congestion (vid. 

 Hyper?emia). Such disturbances are. of course, commonly cor- 

 rected, the vascular constriction and internal congestion together 

 with the vascular relaxation disappearing, and the chilling is 

 realized but for a short time as a sense of cold or brief catarrhal 

 affection by the subject. \\'hy the same adjustment does not 

 occur in all cases is not clear. We only know as a fact that the 

 chilling leaves in the skin itself practically no anatomical altera- 

 tions, that the sensitiveness of the nerves, contractility of the 

 vessel walls, the circulation and perspiration are entirely re- 

 stored, while in the deeper structures the vascular spasm and 

 the succeeding vascular dilatation are apt at times to be pro- 

 longed. Sometimes, as further consequences, local engorge- 

 ments, nutritive faults of the tissues, inflammatory exudates, ex- 

 cessive mucous glandular secretion are to be seen ; sometimes 

 catching cold may manifest itself only by nervous symptoms, 

 functional disturbances and sensations of i>ain and may abso- 

 lutely fail to give any idea concerning the anatomical changes 

 of the tissues. 



Aft'ections which arise in consequence of catching cold are 

 often but transient and are very apt to change their location in 

 a system of tissues, appearing successively at different points 

 along the larger nerves and in muscular regions and at dift'erent 

 joints. For this reason they have been called rheumatic affections. 



[While it is true, as the author indicates, that the varied 

 effects of chilling of the cutaneous surface are not susceptible 

 of a simple explanation, there are certain probable influences 

 which can scarcely be overlooked. The development of congest- 

 ive states in some mucous membrane in connection with the 

 more or less widespread vascular changes beginning in the skin 

 may be held as oft'ering favorable conditions for the more active 

 growth and penetration of some microorganisms, which perhaps 

 in the normal condition, although present, were unable to advan- 

 tageously invade the membrane, and many of the catarrhs which 

 follow refrigeration undoubtedly show clear evidence of such in- 



