FEBRUARY 1, 1914 



107 



his associates called this blue, that red, etc., 

 so that in most eases he can tell the color of 

 objects from its brightness. If, however, 

 two colors tliat are of a decidedly different 

 hue (shade) have the same brightness, then 

 the color blind can no longer see a differ- 

 ence. So we may say the color blind has the 

 ability of distinguishing various colors, but 

 has no sense of color — he sees the colors not 

 as such. 



Hess came through liis extended investi- 

 gations to the conclusion that a sense of 

 color is developed only by the higher order 

 of vertebrate animals, and that the lower 

 order from the fish downward are destitute 

 of the sense of color. Hess used m many of 

 his experiments the bee, and thereby was 

 the controversy whether the bees or the in- 

 sec' s were attracted by the flowers through 

 their bright colors opened anew. 



If, as Hess asserts, the bees are color- 

 I)lind, how are the various experiments by 

 which many scientists formerly showed that 

 the bees were attracted and the sense of 

 location assisted by the colors to be explain- 

 ed? The explanation is very easy. All 

 these experiments showed merely that the 

 bees can distingTiish between various colors 

 the same as the color-blind man, but are no 

 proof that the bees have color sense. This 

 is the new principle on which Hess (and 

 perfectly correct) wants the question solved. 



That is the theoretical part of the ques- 

 tion. Now we will consider some selected 

 experiments which have been recently made 

 with a view of proving the color sense in 

 bees. We will determine the value of these 

 experiments after the new theory developed 

 by Hess. 



The zoologist v. Dobkiewicz made numer- 

 ous experiments which, in their arrange- 

 ments and results, often agreed with those 

 of former investigators. For instance, on a 

 clover-field that was visited by a great num- 

 ber of bees he put up conspicuous artificial 

 flowers of a yellow color that were fllled 

 with honey. These flowers remained unno- 

 ticed by the bees for a long time. The bees 

 when once started to work on a flower are 

 not readily detracted. If, perchance, a bee 

 alighted on one of these artificial flowers, 

 or the experimenter put one on, such a bee 

 returned to the new feeding-place as long 

 as she found something there. She is gtiided 

 by the sight because now she alights also on 

 yellow artificial flowers which contain no 

 honey. 



In a similar way bees may be trained to 

 visit colored disks. In a place in his garden 

 over which the bees of one colony flew 

 regularly, v. Dobkiewicz put up large disks 

 that were covered with red, yellow, and 



orange colored paper. These disks were not 

 noticed by tlie bees. He put a plate with hon- 

 ey near these disks. This plate, with a few 

 bees that had alighted on it, was set upon 

 the yellow disk. The bees were now for days 

 fed on the yellow-colored disk. One day the 

 places of file colored disks were exchanged, 

 but tlie honey remained on the yellow disk. 

 The bees visited only the yelloAv disk — never 

 the orange-colored one that had been put on 

 the place that the yellow had occupied. Fi- 

 nally the disks were again placed as at first. 

 The yellow disk was now without honey, but 

 the red and orange colored disks received 

 honey. The bees visited again the yellow 

 disk, looking in vain for the accustomed 

 honey, while the honey on the red and 

 orange disks was not noticed. The bees liad 

 been trained to look for food on the yellow 

 color. 



The possibility of training bees to visit a 

 certain color is shown very nicely by the 

 following experiment also carried out by 

 V. Dobkiewicz. 



A square box was used having three sides 

 of glass and the fourth one of cardboard. In 

 the cardboard two openings were cut, one to 

 the left side, the other on the right side. A 

 comb of honey was put in the box. The 

 bees had been trained in a former experi- 

 ment to use an opening in a yellow box. On 

 the cardboard sicle of this glass box a yellow 

 disk was put next to tlie hole on the left side 

 (the hole was kept open). The other hole 

 on the right side was m.arked likewise, but 

 a red disk was used, and the opening was 

 closed. Inside both openings wei'e marked 

 just as on the outside. The bees, which had 

 previously been trained to the yellow color, 

 used for entrance and exit the yellow open- 

 ing on the left. After some time the mark- 

 ing was exchanged, the red disk was put to 

 the left and the yellow to the right opening. 

 This change was made not only on the out- 

 side but on the inside also and both holes 

 kept open. The bees were not confused; 

 they used the yellow opening as before, 

 After some time the marking was changed 

 back as it was on the start of the experi- 

 ment, but after a while the marking on the 

 inside of the box was changed, the outside 

 disks remaining unchanged — both holes 

 kept open. The left opening on the outside 

 was now marked yellow and on the inside 

 red. The opening to the right was outside 

 marked red, but on the inside yellow — both 

 holes kept open. Again the bees used with- 

 out hesitation the yellow opening on the left 

 side for the entrance, and the right opening, 

 which was yellow on the inside and red on 

 the outside, was used as exit. We might say 

 that their sense of location, or the entrance 



