168 Beekeeping 



image 1 and (2) that the impressions of the individual facets 

 form a mosaic image. 2 The latter theory has most to sup- 

 port it and is generally accepted. Forel 3 gives an admir- 

 able discussion of these theories and adds considerable evi- 

 dence to support the latter theory. 



As was stated earlier, it is probable that only the rays of 

 light which strike the lens perpendicularly can reach the 

 sensory cells. The image is probably not a distinct one. 

 If an object in motion is within the range of vision of the bee, 

 the image is transferred rapidly from one set of ommatidia 

 to another, which probably accounts for the fact that bees 

 perceive objects in motion more readily than they do still 

 ones. 



In addition to the compound eyes, there are three simple 

 eyes or ocelli (0), which Grenacher 4 states are derived from 

 the same primitive organ as the individual ommatidia of 

 the compound eyes ; in fact, as shown by him and by Forel, 

 compound eyes in some species are replaced by ocelli. 



The parts played by the ocelli and by the compound 

 eyes in the vision of the bee are not clear. From a study of 

 the angles of refraction, it has been inferred that the ocelli 

 are for perceiving near-by objects, while the compound eyes 

 are far-sighted. However, just the reverse has been claimed, 

 and we have no reliable data on this subject. 



It has been shown by numerous experiments and by the 

 experience of beekeepers that bees perceive differences in 



1 Gottsche, C. M., 1852. Beitrag zur Anatomie u. Physiologie des 

 Auges der Fliegen u. s. w. Miiller's Archiv. f. Anat. 



2 Exner, Sigmund, 1875. Ueber das Sehen von Bewegungen und die 

 Theorie des zusammengesetzten Auges. Sitzb. des K. Akad. der Wissensch., 

 LXXII, Abth. III. 



This theory goes back to the work of J. Muller, 1826. Zur vergleichenden 

 Physiologie des Gesichtsinnes. Leipzig. 



3 Forel, Auguste, 1908. The senses of insects. Eng. trans, by Yearsley. 

 London : Methuen and Co. 



4 Grenacher, H., 1874. Zur Morphologic und Physiologie des facet- 

 tirten Arthropodenauges. Nachrichten v. d. K. Gesellsch. d. Wissensch. a. 

 d. G. A. Univ. zu Gottingen, pp. 645-656. 



, 1877. Untersuchungen iiber das Arthropoden-Auge. Beilageheft 



zu d. klinischen Monatsblattern f. Augenheilkunde, XV. Rostock. 



