Both the supernatant fraction and the precipitation one from the fat body of Bombyx mori showed the highest optical density when the density of Triton X 100 was one percent in 0.1M Tris-HCl buffer containing 0.1M NaCl. Accordingly, it was studied on gel filtration eluted with the buffer containing 1% Triton X 100 on a column of Superdex 200. The result showed that this method was more effective than the former method for obtaining the enzyme fraction from the fat body by gel filtration. Moreover, more enzyme fraction was obtained from larval fat body than from larval haemolymph on day 7 in the fifth instar by gel filtration. The fact showed the possibility that the change of neuraminidase activity due to the difference of time differed between the larval haemolymph and the fat body. This research was partly supported by a grant from Tezukayama Gakuen
