Young dogs were divided into the following 3 groups. Group 1 Reared in normal temperature (5 dogs). Group 2. Reared in high temperature and high humidity for 15 days (4 dogs). Group 3 Reared in high temperature and high humidity for 30 days (5 dogs). All these groups received plasmapheresis and recovery of their serum protein was electrophoretically studied for comparison. In total serum protein, 8 days after plasmapheresis, 106% recovery was noted in group 1, 98% recovery in group 2, and 90% recovery in group 3 as compared with that before the procedure. Albumin content on the same day was 90%, 77% and 71% in Group 1, 2 and 3, respectively as compared with that before plasmapheresis. γ-globulin content on the same day was 107%, 100% and 78% in group 1, 2 and 3, respectively as compared with that before the procedure. It is thought that the decrease in albumin is due to a disturbance of liver function and insufficient protein intake as a result of anorexia caused by high temperature and high humidiy, and that, the decrease in γ-globulin is due to mesenchymal functional disturbances caused by high temperature and high humidity. It has been recognized that the patient with Jusho-Shokafuryosho is in a dysergic condition caused by high temperature and high humidity bnd that his γ-globulin content is low. From this experiment it can be recognized that the hypo-γ-globulinaemia is the consequence of mesenchymal functional disturbances caused by high temperature and high humidity.