Abstract
1. In the feeding of the green peach aphids on the leaf stalk of turnip plants the stylet was observed inserted intercellularly in the direction of the phloem, leaving stylet track or salivary sheath which frequently has many branches. Judged from the manner in which the sheath was formed, the direction of extension of the stylet after penetration by bending the stylet, was either to the left or right but not to up-or downward.
2. The stylet was inserted to the surface of the host plant in nearly all instances at a point between two epidermal cells; from which position it extended intercellularly.
3. Onion epidermal membrane was used for making observations on the sequence of extention of salivary sheath and how the branches were produced.
4. Some considerations were given on saliva comprising both the one watery and water soluble and the other coagulable which formed salivary sheath. Considerations were also given on the role of salivary sheath as a substitute for rostrum.
5. In the cases of non-persistent viruses such as turnip mosaic virus, transmission of the virus is said to be effective by a short feeding period of from 5 to 20 seconds by the aphids, and it is also said that during this brief period the stylet is hardly capable of penetrating through epidermal layer, and under this circumstance, the virus is likely to have been transmitted to the plasmodesmata in the intercellular region between two epidermal cells. This is supported by the author on the basis of the fact that the virus inhibitor in Chenopodium album had no influence upon the effect of inoculation by the aphids, in contrast to the cases of inoculation by rubbing method.
