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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. Bcitrag zur Anatomie u. Physiologic des 
Auges dcr Fliegen u. s. w. Muller’s Archiv. f. Anat. 
2 Exner, Sigmund, 1875. Ueber das Sehcn von Bcwcgungen 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 Gesiehtsinnes. Leipzig. 
3 Forel, Auguste, 1908. The senses of insects. Eng. trans. by Yearsley. 
London : Methuen and Co. 
* Grenacher, IT., 1874. Zur Morphologie und Physiologie des facet- 
tirten Arthropodenauges. Nachrichten v. d. K. Gesellsch. d. Wissensch. a. 
d. G. A. Univ. zu Gottingen, pp. 645-656. 
- , 1877. Untorsuchungen iiber das Arthropodeu-Auge. Beilageheft 
zu d. klinischen Monatsbliittern f. Augenheilkunde, XV. Rostock. 
