PURPOSE: To separate a biologically active material for use as a stimulating material in the segeneration of heart muscle and a growth controlling material, by purifying a manow or spleen of domestic animal, followed by treatment.

CONSTITUTION: A narrow or spleen of a domestic animal is dipped into a buffer solution in the pH of 3.4W7.5 or in 30W99.5 wt.% alcohol solution to prepare a dipped solution, which is dialyzed for a night. Hydrogen sulfide gas is introduced into the dialyzed solution so that iron is precipitated and removed. Colored impurities are removed by adding 0.01W0.5 wt.% based on a liquid amount of active carbon to the solution or by using a decoloring resin. The solution thus obtained is directly subjected to freeze drying or after being passed through Sephadex or an ion exchange resin to separate biologically active material. This material is yellow solid powder, has 14 wt.% of nitrogen, and consists mainly of a protein exhibiting a maximum absorption in a wave length of 270W280 mm.