Abstract
(1) The wave shape of the flow of liquid silk in the silkgland at the middle division of the ripened larvae could be observed for which discussion based upon the hydrodynamical views has been made. The wave mentioned above is different thing with that of so called “plait” which is said to give cause for becoming the divisible fibres (Fig. 1 & 2).
(2) The tensile stress in the silkgland wall seems to be represented as following order of their magnitude: middle section of middle division > posterior section of middle division > anterior section of middle division > posterior division > anterior division (Table 1).
(3) It is presumable that the pressure of liquid silk in the gland cavity, which has raised to some degree, becomes an incentive of spitting the silk out. Explanation for the longitudinal splitting of silkgland wall at middle division, which is caused by the stop of spitting the silk out, is able from points of the pressure of liquid silk, the elasticity of gland wall and the tensile stress of gland wall.
(4) The degree of elasticity of silkgland wall and the shape of gland cavity at the anterior and posterior sections of middle division seem to be convenient for the liquid silk to enter from posterior division into middle division and to move from middle division to anterior division together with spitting the silk out (Fig. 3).
(5) The internal friction of liquid silk and the friction of liquid silk against the silkgland wall has been discussed.
