1. Glycogen synthesis in the ovary of Bombyx mori is accelerated by the diapause hormone.
2. Such glycogen is derived, by way of the trehalose of the haemolymph, from carbohydrate in the fat body.
3. Extirpation of the suboesophageal ganglion has the converse effect: a fall in glycogen in the ovary and an increase in blood trehalose and fat-body glycogen.
4. Mobilization of fat-body glycogen is dependent on the presence of the ovaries, and of the suboesophageal ganglion.
5. The same results can be obtained in male pupae after the implantation of ovaries.
6. These observations on carbohydrate metabolism confirm the belief that the ‘target organ’ of the diapause hormone is the ovary itself. The changes in other tissues are due to feedback.