STUDIES ON THE INTEGUMENT OF THE SILKWORM, BOMBYX MORI. VII. THE PERMEABILITY OF THE INTEGUMENT TO OXYGEN AND CARBON DIOXIDE IN VIVO

¹ Sericultural Experiment Station, Suginami-ku, Tokyo, Japan

1. From the results of measurements of O₂ uptake and CO₂ output in the sealed silkworm, it was confirmed that the gases penetrate through the integument both in the larva and pupa. The rate of O₂ uptake as well as CO₂ output is reduced to about one-fiftieth of the controls in the sealed silkworm. The R. Q. value of such silkworms ranged from 1.00 to 1.20 in the larva and was about 1.50 in the pupa. The rate of respiration became lower with the time lapse after occlusion, the decrease being more remarkable in the larva than in the pupa. Throughout the larval and pupal stages, the rate of O₂ uptake decreased less than that of CO₂ output.

2. The permeability of the skin rubbed just before occlusion increased a few times, the ratio being a little higher in the larva than in the pupa. The rate of increase in CO₂ output was about one and one-half times that in O₂ uptake both in the larva and pupa. The decrease of the volume of measured gases seen with the time lapse in the rubbed material was not so remarkable in the pupa, and the rate of decrease in CO₂ output was relatively high in the larva. From this it was shown that the increase of cutaneous respiration by abrasion was not so remarkable as compared with that of water transpiration through the integument.

3. Some observations in relation to cuticle rubbing were briefly outlined.