In the observations of the skin capillary blood vessels at the root of finger nail the author pursued the characteristics in various diseases and also made an attemp to observe changes in the capillary blood vessel picture caused by the use of depressants and obtained the following results. 1. Those showing mostly the normal pattern of the blood vessel picture were pulmonary tuberculosis, gastro-intestinal inflammations, habitual constipation, the adhesion of intestines and chronic hepatitis. 2. Those showing mostly the shrunkendilatated form were bronchitis, bronchial asthma, heart disesses, hypertension, arterial sclerosis, acute and chronic nephritis, nephrosclerosis, hyper-acidism, gastro-duodenal ulcers, gastro-rectal cancer, liver cirrhosis, hepatopathey, diabetes, Basedow's disease and neurosis. 3. Those characterized by the dilatated form were such diseases as influenza, gastroptosis, gastro-atony, acute hepatitis, dyskinesy of gall-bladder, beriberi, and autnonomic imbalance. 4. In hypertension capillary blood vessels are dilated and the pressure fals with the use of depressants, but in nonhypertensive cases no marked changes can be recongized in the capillary vessel picture nor in the blood pressure. 5. In the cases positive to the cold pressor test the majority show the shrunken form of the capillary blood vessel picture, but no special realtionship between the age and blood pressure can be recognized. 6. In those not showing any marked changes of the capillary blood vessel picture even at advanced age the blood pressure adjustment function seems to be maintained relatively well.