It hasbeen reported by ISHIKAWA and HIRAO (1963) that among three seneilla styloconica of the maxillary lobe of silkworm larva two longer ones have quite different contact chemoreceptors from each other, one being called sugar sensory hair and the other water sensory hair. The former responds to sucrose, inositol and salts, while the latter seems to be excited by repellent substances, water and some kinds of salts.
This finding let us to examine the functional differentiation of the two sensory hairs of a “nonpreference” mutant which cannot discriminate other plant leaves from mulberry. The mutant was obtained by TAZIMA, one of the authors, in 1953 after X-irradiation. It is controlled by a single Mendelian dominant gene which is associated with a recessive lethal. The mutant stock has been maintained for about 20 generations by sibling heterozygotes orinter se. Both normal and mutant types segregate in the same batch of this stock in every generation.
The response of the receptors in the two sensory hairs has been recorded electrophysiologically for both mutant and normal by stimulating with several water soluble extracts of plant leaves and some pure chemicals.
No noticeable difference have, however, been found between the normal and mutant for both hairs. Furthermore, in both type individuals no positive response was observed to isoquercitrine, which according to HAMAMURAet al.(1962) is an attractant of this insect.
Two possibilities might, therefore, be considered regarding the loss of food-preference in this mutant:
1) Functional abnormality in the central nervous system, because no abnormality has been revealed for two sensory hairs in this mutant so far as the present experiment is concerned, or alternatively;
2) Abnormality in the sensory organs for other functions than those tested in this experiment.

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In the inner walls of the thread pressing portion of the spinning tube of the silkworm, the dorsal chitinous plate, the ventral chitinous plate and the border chitinous plate are formed. All of these three types of chitinous plates are formed in the larvae of final instar. The border chitinous plate is never formed during other larval instars than the final one.
The spinning tube of a tetramolting larva on the first day of the third instar, which normally molts twice before the border chitinous plate is formed, was transplanted into the larva on the second day of the fourth instar. The growth of the host larva was normal and the transplanted spinning tube molted simultaneously when the host molted to the fifth instar. In the transplanted spinning tube, the border chitinous plate was formed as normal as in the spinning tube of the host larva.
It was found that the epidermal cells of the spinning tube, when forming the border chitinousplate, is controlled by the hormones that control growth of the larva.

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In this paper, a few observations on behaviour of mycelia of mulberry rust, Aecidium mori BARCLAY, in host tissue were described. The results obtained were as follows:
1. It could easily be found out that the primary infection was, distinctly in appearance, different from the secondary infection in symptoms of the disease. Namely, in the former case the disease was developed from the base of spring budding shoot infected last year, to every part of itself, in the later it was distributed somewhere on leaves, petioles, and younger portions of twigs. The author showed that each of these symptoms was caused by different process of mycelial growth (Fig. 1). In the primary infected shoot, the masses of mycelia grow at first near the vascular bundles of the shoot in parallel with them, and a little later the mycelia departed from the masses spread radially into the tissue around (Pl. I A, B). The mycelia reached just the under region of epidermis form the aecidia there (Pl. I B). Whereas, in the secondary infection, mycelia penetrating epidermic layer, spread gradually around the penetrated point (Pl. I C).
2. Mycelia growing in the intercellular spaces of the host tissue formed haustria in host cells (PI. F, G). Mycelial growth and formation of haustria were more abundant in the younger parenchyma of the host.
3. It may be possible that mycelia can use directly their food materials from sieve tube of the host. This is based on facts that in the primary infection in spring, mycelial growth is initiated along the vascular bundles, and in the secondary infection, only the residual mycelia are still alive around the vascular bundles in the neighbourhood of the necrotic tissues resulting from infection.

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