家蚕

On the second article of the antenna of the domestic silkworm, there are normally three tactile papillae and two sensory hairs. Two of the papillae are large and unjointed, while one is small and jointed. One of the sensory hairs is longer and outward in position, the other is shorter and situated inwardly. Typically, two jointed and two unjointed papillae are found on the tip of the third article of the antenna. These papillae and hairs are subject to meristic as well as to symmetrical variations. Of 208 antennae from 111 individuals, 143 (68.7 %) were normal, and 65 (31.3 %) abnormal either in the number or the position of the papillae or hairs, or in both. The meristically more variable papillae are the unjointed ones on the second article, which had from one to three extranumerary unjointed papillae in 15 cases. Except in a single case, no individual has yet been found with fewer. The symmetrically more variable papilla is the small jointed one on the second article, the translocation taking place around the posterior unjointed papilla in the direction of dextral winding in the right antenna, and in the sinistral direction in the left antenna. The sensory hairs sometimes vary in relative position, i. e. they approach each other. This is proved to be accomplished by translocation of the shorter rather than the longer hair. Variations of the tactile papillae on the third article have also been observed, but they were not so conspicuous as those on the second article, owing to their crowded distribution on the small tip of the third article. The variations mentioned above occ u r either independently of each other, or simultaneously. The latter case is called by us "double variation." The observed variations may be classified as follows: (snip)