By Observing the changes in the Donaggio reaction at the time of digestion and hydrochloric acid hydrolysis of crystal egg-white albumin by proteolytic enzymes and performing the quantitative analysis of Anderson's mucoprotein in the rabbits administered with adrenalin and ammonium chloride, the author obtained the following results. 1. When crystal egg-white albumin is digested with pepsin, trypsin, or papain, it has been recognized that the Donaggio reaction value decreases in parallel with the lapse of the digestion times. 2. When crystal egg-white albumin is hydrolyzed with hydrochloric acid, the Donaggio reaction value decreases along with the lapse of hydrolysis time, but the decrease in this instance is greater than that in the case of the digestion by proteolytic enzymes. 3. From these results it is assumed that for the Donaggio reaction at least protein molecules must be present. 4. The hourly excretion of Anderson's mucoprotein reveals an increase in the amount after the administration of adrenalin or ammonium chloride.