30 ^ UNIVERSITY OF MISSOURI STUDIES [2l8 



through the center of the eye unmistakable ommatidia are pres- 

 ent, presumably those belonging to the part of the cornea that 

 had not been removed. Fig. 26 shows the cornea to be almost 

 normal in shape and position, although much reduced in size. 

 It is significant that there is no indication that the injured optic 

 ganglion is being regenerated, and also that the cuticle is just as 

 heavily developed over the corneal portion as over the stalk por- 

 tion of the eye. But perhaps the most striking feature is what 

 seems to be an increase of muscle tissue along one side and 

 reaching almost to the top of the eye. Fig. 26 a, PI. Ill, shows 

 a section taken eccentrically and from the side which is almost 

 destitute of ommatidial structure. Almost the entire interior of 

 the section is taken up by bands of muscle fibres (m). To the 

 right, there is still the remains of the optic ganglion (gl) and 

 around the periphery are loose connective tissue fibres (c. c.) ; 

 inside the cuticle is a well defined hypodermis, and in the upper 

 part of the figure the irregular remains of some of the crystalline 

 cones. The large amount of muscle tissue can scarcely be ex- 

 plained as due to the plane in which the section chanced to be 

 taken ; for the normal eye of the opposite side was cut in connec- 

 tion with the regenerated one, and shows no such preponderance 

 of muscle. Besides, among the large number of normal eyes 

 that I have sectioned in different planes, none show any such de- 

 velopment of muscle. It seems evident that more than the nor- 

 mal amount of muscle tissue is developing here at the expense 

 of other tissues. Although only twenty-four days have elapsed 

 since the removal of the part of the eye, new muscle tissue has 

 completely developed. This may be seen by reference to Fig. 41, 

 PI. IV, which shows some highly magnified muscle fibres taken 

 from region a, Fig. 26 a, PI. III. 



Fig. 35, PI. IV, shows both normal and regenerating eyes 

 of the crayfish referred to above. The entire cornea was 



