10 STUDIES IN GENERAL PHYSIOLOGY 



On either side of the spectrum the animals remained at rest. 

 In addition to this, Bert made another experiment. He 

 had a spectrum projected on a trough, and observed how 

 the animals distributed themselves over the different parts 

 of the spectrum. 



L'immense majority se placa dans le jaune, le vert, Forange; 

 une assez grande quantity se voyaient encore dans le rouge, un 

 certain nombre dans le bleu, quelques-unes de plus en plus rares a 

 mesure qu'on s'eloignait dans les regions plus re"frangibles du 

 violet, au del& du rouge, au del& de 1'ultra-violet ; dans les regions 

 invisibles, en un mot, on n'en trouvait que d'isole"es en promenade 

 accidentelle. 



From these facts Bert concluded that Daphnia behaves 

 in the spectrum much as a man would, who, when reading a 

 book, would move into the brightest part of the spectrum, 

 into the yellow light. 



Lubbock repeated Bert's experiment on Daphnia. 1 One- 

 half of a dish was covered by a yellow screen; the other 

 half was left uncovered. In the uncovered half 1,904 

 animals collected, while 3,096 gathered under the yellow 

 screen. From this Lubbock concludes that Daphnia has a 

 "preference" for "yellow." But one would suppose that in 

 the uncovered part of the dish there was at least as much 

 yellow light as under the yellow screen; or did the majority 

 "hate" the blue light? 



When Lubbock covered one-half of the trough with 

 blue glass and left the other uncovered, he found 2,0-16 

 animals under the blue glass, and 2,954 in the uncovered 

 part of the trough. Whether one is to conclude from this 

 that blue light is in the sense of Lubbock "disagreeable" to 

 Daphnia is not stated. When half of the trough was 

 covered with red glass, there collected 1,928 animals under 

 the red glass, while 3,072 collected in the uncovered por- 



i LDBBOCK, " Die Sinne und das geistige Leben der Thiere," Internationale 

 wissenschaftliche Bibliothek, Vol. LXVII (1889). 



