In this experiment it has been explained that the copper-sulphate reaction of horses serum infected with infectious Anaemia differes scarcely from that of the healthy horses, and that the copper-sulphate reaction seems to be characteristic to the Encephalitis serum. The reason is likely to be explained from the fact the decrease of serum sugar in the encephalitis serum is quite remarkable. In the case of the infectious Anaemia serum, the decrease of albumin and the decrease of other proteins is shown, though the change of serum sugar content is rather variable. Further investigation on this point shall be continued from every angle.