108 



GLEANINGS IN BEE CULTURE 



and exit in this experiment, was governed 

 entirely by the yellow color. 



These experiments proved what older in- 

 vestigations had already shown — tlie bees 

 were in fact locating (finding their way) by 

 colors. But do these experiments prove that 

 the bees possess the sense of color? No, the 

 bees might be color blind and react just as 

 they did. By these, as by older experiments, 

 was proven only that the bees can distin- 

 guish some colors. Whether they see colors 

 as such is a different question which may 

 also be solved by experiments, as we shall 

 see by the following investigations of the 

 zoologist K. v. Triseh, Munich. He takes 

 issue with the views of Hess regarding the 

 color sense of animals. He has also made 

 experiments with bees to disprove the view 

 of Hess that the bees have no sense of color. 

 K. v. Frisch in arranging his experiments 

 was guided by the following jDrinciple : 



A color-blind eye sees the colors only as 

 various shades of gray. It sees no colors — 

 only colorless brightness of variable inten- 

 sity (farblose Helligkeitswerte). 



Therefore to each color — for instance yel- 

 low — there must exist a certain shade of 

 gray which a color-blind eye can not distin- 

 guish from yellow ; both Avill appear of the 

 same colorless brightness ; both will have the 

 same " farblosen Helligkeitswert." 



K. V. Frisch took 30 pieces of gray joapers 

 wliich showed all the various shades of gray 

 from white to black. These papers, all of 

 equal shape and size, were fastened on a 

 table, not in the regular order of the shades 

 of color, but at random. Among them were 

 also placed two papers in shape and size as 

 the others but of yellow color. On each 

 paper a small dish was placed. Those on 

 the gi'ay papers were kept empty, while the 

 two dishes on the yellow paper were filled 

 with sugar syrup. As soon as the bees of a 

 nearby colony discovered the syrup on the 

 yellow paper they began to visit these two 

 dishes in large numbers. 



The bees were fed for two days on the 

 yellow paper to train them to the yellow 

 color. The places of all the papers were 

 frequently changed so the bees might not 

 learn to locate the syrup after the order in 

 which the papers were arranged on the 

 table (to eliminate as much as possible 

 every thing for guidance except the color). 

 The bees alighted always on the yellow 

 paper without the least hesitation. 



The two yellow papers and the dishes 

 were taken away and two new yellow pa- 

 pers were put in other places. Two new 

 dislies were put on these yellow papers. 

 'IMiis was done so there would be no odor 

 to attract or guide the bees. Now all the 



dishes on the gray and yellow papers were 

 filled with syrup. 



From this experiment the following de- 

 duction was made : If the bees are color 

 blind they will see the yellow only as a gray, 

 and must mistake some one or more of the 

 30 gray shades for the yellow. The bees, 

 however, made no such mistake; they visited 

 only the two yellow papers and paid no 

 attention to the many syrup-dishes on the 

 gray papers. In locating the syrups they 

 were guided only by the yellow color. 



After the syrup had been removed from 

 the dishes on the gray papers and the bees 

 fed for some time on the yellow, the dishes 

 with the syrup were removed from the 

 yellow and replaced with empty dishes, so 

 that all the papers on the table contained 

 only empty dishes. The bees visited the two 

 dishes on the yellow papers in great num- 

 bers, searching in vain for syrup, but not a 

 bee alighted on one of the gray papers. 



In the preceding experiment it has been 

 proven that the bees recognize tlie yellow 

 paper not only by the colorless brightness 

 but by the yellow color. K. v. Frisch show- 

 ed further by experiments that the same 

 results can be obtained for blue. 



Tlie following is a strong proof. After 

 bees had been trained to blue the two blue 

 papers wei'e removed and two new blue 

 papers were put on another place. All the 

 30 dishes on gray paper were filled with 

 syrup ; only the two dishes on the blue 

 paper were left empty. The bees visited 

 the empty dishes on the blue papers in great 

 numbers, and searched industriously for 

 syrup, while the dishes with the syrup on 

 the gray papers were for a long time not 

 noticed. 



Against the preceding experiments the 

 following objection might be raised. Al- 

 though the shades of the 30 gray papers 

 were so nicely graded that the human eye 

 could barely distinguish the two nearest 

 shades, perhaps the eye of the bee is so 

 delicate for perceiving differences in color 

 brightness that even if it sees no color it 

 can readily distinguish the yellow and blue 

 paper by its shade of brightness. If that 

 were so, then the bees could be trained to 

 one particular shade of gray. K. v. Frisch 

 made the following experiments : 



The bees were fed nine days exclusively 

 on gray No. 15. After removing the syrup- 

 dish from No. 15, and replacing it with an 

 empty one, the bees were searching for the 

 syrup on the various gray papers without 

 any preference to No. 15. The objection to 

 the experiments is therefore groundless. 



With the above-recited experiments theie 

 has doubtless been proven that the bees 



