FUNDAMENTAL STUDIES ON THE FISH LAMP 231 



out that the ratio of the fish gathering rates for the two Hghts was pro- 

 portional to the ratio of the spectral luminosities of the two lights. 

 Moreover from the ratio of spectral luminosity to radiant energy, the 

 "visual efficiency" Avas calculated, and in the case of Spheroides rubripes, 

 green light showed the largest visual efficiency, that of blue light was 

 next to green, and that of red light was smallest. 



Though radiant energy of red light was 22 times as much as that 

 of green light, its visual efficiency was no more than 1/62 of that of 

 green light (J. Konishi). 



Studies on the influence of repeated experiments on the aggrega- 

 tion of fish to a fish lamp were carried out; the young Girella punctata, 

 which was repeatedly made at intervals of ten minutes, made clear 

 that the influence of a preceding experiment was held over to the suc- 

 ceeding one, while in the experiment of young Scomberomorus nipho- 

 nius made at intervals of 30 minutes, no such influence was seen, and 

 the fish gathering rates of Scomberomorus, Oplegnathus and Monacan- 

 thus under the stationary light attained maximum in a definite time, 

 and then became stabilized at this maximum value (H. Kobayashi). 



The experiment of turning on and off at any intervals two lamps 

 which were situated inside the water tank (3 m. in length, 64 cm. in 

 width, 40 cm. in depth) was done. Aplocheilus latipes (fresh water 

 fish) and Girella punctata showed the greatest gathering rates to the 

 lamps, which had the most appropriate intensities for them when two 

 lamps were turned on and off. However, the gathering rates, as a whole, 

 decreased little by little in proportion to shortening of the interval 

 (T. Niki). 



The gathering rates of Spheroides and Mugil show almost the same 

 tendencies of sectional distribution as the type U in the limited length 

 of water tank (3 m. in length, 25 cm. in width and depth) and the 

 light source set at the end of it, used in this experiment, the type U of 

 the curve of sectional distribution of fish in the tank is divided into two 

 meanings; and those are positive gathering rate which decrease expo- 

 nentially in proportion to the distance from the light, and negative 

 gathering rate which, on the other hand, increase exponentially to the 

 opposite side of the light. The value of the light intensity at which fish 

 gathering rates are highest was 55 lux in Spheroides; both in the day 

 and in the night, the values were 15 lux in the night and 87 lux in the 

 day in Mugil (S. Nagata). 



The present writer further studied with K. Uno on the influence 

 of the moonlight on the gathering rates to the fish lamp as follows: 



The relation between the moonlight and the fish lamp upon the 

 gathering rates of fishes has been studied in the laboratory and in the 



