CH. XXI.] ANGIO-NEUROSES. 3 11 



It is almost impossible to over-estimate the importance of the 

 study of vaso-motor phenomena, as a means of explaining certain 

 pathological conditions ; our knowledge of the processes concerned 

 in inflammation is a case in point. 



Disorders of the vessels due to vaso-motor disturbances are 

 generally called angio-neuro&es. Of these we may mention the 

 following : 



Tache cerebrate is due to abnormal sensitiveness of the vascular 

 nerves ; drawing the finger-nail across the skin causes an imme- 

 diate wheat, or at least a red mark that lasts a considerable time. 

 At one time this was considered characteristic of affections of 

 the cerebral meuinges like tubercular meningitis, and was 



Fig. 291. Boy's Oncograph, or apparatus for recording alterations in the volume of the 

 kidney, &c., as shown by the oncometer a, upright, supporting recording lever I, which 

 ia raised or lowered by needle 6, which works through /, and which is attached to the 

 piston '. working in the chamber d, with which the tube from the oncometer com- 

 municates. The oil is prevented from being squeezed out as the piston descends by a 

 membrane, which is clamped between the ring-shaped surfaces of cylinder by the 

 screw i working upwards ; the tube h is for filling the instrument. 



consequently called the "meningeal streak." It, however, occurs 

 in a variety of pathological conditions of the nervous system 

 both cerebral and spinal. 



In certain conditions which lead to angina pectoris the pain in 

 the heart is due to its being unable to overcome an immense 

 peripheral resistance, and the condition is relieved by the adminis- 

 tration of drugs like amyl-nitrite or nitro-glycerine, which relax 

 the vessels and cause universal blushing. 



RaynaucVs disease is one in which there is a localised constric- 

 tion of the vessels which is so effectual as to entirely cut off 

 the blood supply to the capillary areas beyond, and if this 

 lasts any considerable time may lead to gangrene of the parts 

 in question. 



