460 STEFAN K0Pe6 



In this manner I also deprived the caterpillars of the larval optic 

 ganglia (as to method of operation, cf. Kopec, '18). Some of 

 the caterpillars underwent pupation and developed to adult 

 forms of moths. In all the specimens of these moths, or of their 

 pupae, the eyes were quite normally developed macroscopically 

 (cf. fig. 1, representing the eyes of brainless moth). In dissections 

 of eyes which developed without the brain, only a more or less 

 distinct wrinkling of the surface of the eye may often be noticed. 

 I consider this deformation to be due only to the mechanical 

 difficulties experienced by a brainless animal in drawing its 

 injured head from the skin of the caterpillar or pupa during its 

 metamorphosis. 



Also microscopical researches have demonstrated the normal 

 structure of 'brainless' eyes (cf. figs. 2. and 3, representing dissec- 

 tions of eye which developed without the brain, with figs. 4 and 

 5 giving analogous dissections of normal eyes). Both the number 

 of ommatids and the size and form of all components of the 

 compound retina were in no wise different from those observed 

 in normal circumstances. The arrangement of the pigment is 

 somewhat different in figure 3 of the ' brainless' eye and in figure 

 5 of a normal one. But also in normal specimens we may ob- 

 serve individual fluctuations in this arrangement of the pigment, 

 due probably to the time at which they were killed. 



On the interior surface of the normal eye I always found the 

 layer which is called by Berger ('78) 'the nerve-bundle layer' 

 (Nervenbiindelschicht) to be well developed. In this layer I 

 have discerned two distinct parts: an external layer of single 

 bundles, consisting of a relatively small number of nerve fibers 

 coming directly from the retina of the eye (fig. 4, s.n.l}.) and an 

 internal one, which I might call the layer of compound bundles 

 (c.n.h.). The compound bundles are made up of single bundles 

 which are in both layers distinctly separated from one another and 

 run regularly to the interior of the head, radiating in the direction 

 of the optic ganglion. The arrangement of the single bundles 

 does not evidence any changes in the brainless insects (fig. 2, 

 s.n.h.), while the compound bundles always behave wdth remark- 

 able irregularity. These latter bundles have an abnormal 



