A simple procedure for partial purification of silkworm brain hormone starting with
heads of Bombyx moths is described. The method is unique in that it can supply samples
with a definite activity without chromatography and bioassay during the purification process.
The titer of brain hormone in every batch is 30~ 40 Samia units/head (specific activity, 1 ~ 2 [lg/
Samia unit). Some chromatographic behaviors of the hormone are also reported.