The author (1936) found incomplete moulting in a non-moulting strain of the silkworm, which is characterized by (1) inactivity in oenocytes, (2) change in the body weight and in the frequency of cell division in hypodermis and fatty tissue, apperently corresponding to and a little later than the moulting period of the normal worm, and (3) glycogen content in the Malpighian tubes which increases very much just before death owing seemingly from starvation.
When normal and newly hatched silkworms are reared in inadequate feeding, the body weight of the worms follows one of the three courses mentioned below according to the degree of inadequacy.
If the worms are fed extremely inadequately, for instance 30 minutes per day, the weight of worms increases at the beginning very slightly then it decreases gradually until death. If the worms are fed sufficiently, 6 hours or more per day, the weight of worms increases until moulting, decreases slightly during moulting and increases again with the beginning of the next instar.
If the worms are fed intermediate between the two cases mentioned above, the worms undergo retarded moulting or non-moulting. In this case, most non-moulting worms show the change in body weight very similar to that in the incomplete moulting worms of the non-moulting strain which was reported formerly.
In the non-moulting worms obtained by inadequate feeding and showed characteristic change in body weight the oenocytes were similar to those in the normal worms except the size of the cell. In this artificial non-moulting worms there occurs cell division in fatty tissue comparable with the hereditary non-moulting worms.
From this expriment, the author concludes that the hereditary non-moulting is brought about by the ill nutrition which is correlated with the abnormality of oenocytes in some way. In the artificial non-moulting worms the glycogen content showed very high level just before death as reported in the hereditary non-moulting ones.