GAMBARAN HISTOPATOLOGIS LIMPA TIKUS PUTIH (Rattus novergicus) JANTAN DIINFEKSI Trypanosoma evansi DAN DIBERI EKSTRAK KULIT BATANG JALOH (Salix tetrasperma Robx) (Histopathological finding of Rat (Rattus novergicus) Spleen Infected with Trypanosoma evansi and Treated with Willow Bark (Salix tetrasperma Roxb) Extract) (Universitas Syiah Kuala, 2015)