or a cyanoalkyl group such as cyanomethyl 2 cyanoethyl or 3 cyanopropyl if n is an integer greater than 10 the amount of aminoalkylpolysiloxane that must be added increases this increases the cost of manufacturing the aminogroup containing polysiloxane so that it is no longer a profitable industrial process it is particularly to be preferred that n is an integer from 4 to 8 the basic catalyst used in this invention may typically be an alkali metal oxide such as sodium oxide potassium oxide or lithium oxide an alkali metal hydroxide such as sodium hydroxide potassium hydroxide or lithium hydroxide an alkali metal alkoxide such as sodium methoxide sodium ethoxide or potassium ethoxide an alkali metal silanolate such as the potassium salt of methylsilanetriol or the potassium salt of phenylsilanetriol tetramethylammonium hydroxide or tetrabutylphosphonium hydroxide or a mixture of two or more of these compounds the amount of basic catalyst used in this invention is preferably 0 001 0 1 weight but from the viewpoint of obtaining a constant polymerization speed more preferably 0 005 0 05 weight with respect to the amount of cyclic organopolysiloxane used in this invention the aforesaid reactants can be heated so as to promote the reaction by shifting the equilibrium point between the cyclic organopolysiloxane and aminoalkylpolysiloxane in this case there is no specific limitation on the heating temperature but it is preferably 80 u00b0 180 u00b0 c and more preferably 120 u00b0 150 u00b0 c in this invention the aforesaid reaction can also be performed in an organic solvent suitable solvents being for example toluene and xylene according to the manufacturing method of this invention there is no rapid increase in the viscosity of the reaction.