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| 佐々木忠次郎からエドワード・S・モースへ |
Chujiro Sasaki (1857-1938) stands as a noteworthy figure, having been a protégé of Edward S. Morse during his tenure at the University of Tokyo. As a student in 1877, Sasaki engaged in excavations and surveys at the Omori Shell Mound. In the subsequent years, he also explored the Okadaira Shell Mound, a site of significant archaeological import. Graduating from Tokyo University in 1881, Sasaki pursued further studies in Germany over a span of two years. His academic journey led him to eventually become a professor specializing in zoology, entomology, and sericulture at the Imperial University Agricultural College in 1893.
A postcard dated May 3, 1916, from Chujiro Sasaki to Edward S. Morse. The handwriting is unquestionably the work of two individuals; Sasaki wrote the main portion, while another hand addressed the bottom. The differences in penmanship are evident.
Tokyo, 3 May 1916
Dear Professor!
Much thanks are due to your kind sending of paper on the Fireflies Flashing. I am always glad to receive your works, which indicate your healthy condition.
Yours very faithfully,
Agric. Coll.
Tokyo Imp. Univ.
Tokyo (Komaba),
Japan
Sasaki must have been referring to the article 'FIREFLIES FLASHING IN UNISON' (published in SCIENCE on Feb. 4, 1916). Below is its full text:
FIFTY years ago in Gorham, Maine, while walking along the road I passed an open field and noticed to my astonishment hundreds of fireflies flashing in perfect unison. I watched this curious sight for some time and the synchronism of the flashing was unbroken. Many times after I have watched these luminous insects, hoping to see a repetition of this phenomenon, but the flashes in every instance were intermittent. Since that time I have read about these insects in various books without meeting any allusion to this peculiar behavior.
At last I have found a confirmation of my early observations. In Nature of December 9, page 414, is the report of an interesting paper read before the South London Entomological and Natural History Society by K. G. Blair entitled "Luminous Insects " in which reference is made to the remarkable synchronism of the flashes in certain European species of fireflies. The explanation offered as to the cause of this behavior seemed to me inadequate. One often notices in the stridulation of the Grillide the perfect time the insects keep in their concerts and it seems likely that the same impulse must animate these flashing beetles, and the light emitted could be more easily followed than the sound.
(Morse continues) The following is an extract from Mr. Blair's paper:
Apart from its principal function in securing the proper mating of the sexes, the light seems also to be largely used, at any rate by the males, for purposes of display. Where the powers of luminosity are largely developed in this sex the emission of the light is usually of an intermittent flashing type. It has been noticed in various parts of the world that these flashing males tend to congregate in large companies, and that all the individuals of one of these gatherings will flash in concert. All the fireflies around one tree or group of trees, for instance, will flash together, while those around a neighboring tree will be pulsating to a different time. This feature has been observed of a European species of Luciola (though Mr. Main and myself were unable to detect anything of the sort with L. italica at Lugano), of an Indian lampyrid genus not stated, and of the genus Aspidosoma in South America. The American species of Photinus and Photuris do not seem to possess the habit.
The exact reason of this flashing in concert, or the method by which it is brought about, have not been ascertained. It has been suggested that the light is not really intermittent in character, but merely appears so owing to its being alternately masked and exhibited by movements of the creature's body, and that a slight puff of wind might perhaps affect all the members of a company and cause them all to conceal their lights at once. Though this explanation of the intermittent character of the light applies well enough to Pyrophorus, an insect we shall shortly consider, it is certainly not applicable to these Lampyride. It is true the light is not absolutely extinguished between the flashes, but it is so diminished as to become practically dark; moreover the flashing in unison is too regular to be caused by chance puffs of wind. A more probable explanation of the phenomenon is that each flash exhausts the battery, as it were, and a period of recuperation is required before another flash can be emitted. It is then conceivable that the flash of a leader might act as a stimulus to the discharge of their flashes by the other members of the group, and so bring about the flashing concert by the whole company.
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