1905.] NATURAL SCIENCES OF PHILADELPHIA. 123 



STRUCTURE AND DEVELOPMENT OF THE COMPOUND EYE OF THE 

 HONEY BEE. 



BY EVERETT FRANKLIN PHILLIPS, PH.D., 

 Harrison Fellow for Research in Zoology, University of Pennsylvania. 



Contents. 



I. Introduction. 

 II. Methods. 

 III. Adult Form of Eye and Ommatidium. 

 [IV. Embryology and Structure in Detail. 



1. The Entire Eye. 



2. Arrangement of Ommatidia. 



3. Hair Cells. 



V. Retinular Ganglion. 

 VI. The Ommatidium. 



1. Larva. 



2. Pupa. 



a. The Retinula. 



b. The Cone Cells. 



c. The Corneal Pigment Cells and the Lens. 



d. The Outer Pigment Cells. 



3. The Adult Ommatidium. 



a. The Retinula. 

 VII. Homologies of Component Parts. 

 VIII. Summary. 

 Literature. 

 Explanation of Plates. 



I. — Introduction. 



The morphology of the compound eye has puzzled zoologists for 

 years, and much work has been done on the subject, but so diverse 

 are the views held by the various investigators in the field that we are 

 far from a final solution of the problem. With a view to adding some 

 evidence from the embryological point of view this work was begun, 

 in the belief that a detailed examination of this one insect eye would 

 throw some light on the adult morphology. 



The eye of the common honey bee. Apis meUifcra; is particularly 

 favorable for embryological work, since its growth is gradual and the 

 steps of development well marked out. The material is also easily 

 obtained, and the various stages of growth can be distinguished by 

 the external appearance of the larvae and pupse. It is also favorable for 

 a comparison with the development of the eye of Vespa, which was 

 described by Patten, since it is desirable to find how far his results 

 can be verified on a closely related form. The large number of omma- 



