52 



Note the fluid spaces in both specimens, and the shrunken, 

 f iberous appearance of the brain and the amorphous , sunken 

 eyes of the older specimen. The optic stalk, optic nerve, and 

 flattened, unstructured mass of developing eye tissue of a 

 younger pupa (corresponding in age to the specimen in Fig 

 10) are shown in Fig 11. 



The destruction or inhibition of development of the 

 cuticle in infected pupae is shown in Figs 13-16. The healthy, 

 developing cuticle with its trophic microvilli and two 

 pores (Fig 13) is completely absent in the diseased specimen 

 (Fig 14). The microvilli of the latter extend randomly 

 into the fluid space. Details of the microvilli are pre- 

 sented at higher magnification in Figs 15 and 16. The tis- 

 sues shown in these electronmicrographs are from the head 

 where pathognomonic clearing develops. In tissues from 

 the gaster, where little or no clearing occurs, some cuticle 

 is present (Fig 26) . 



The structures of a healthy, developing pupa eye and 

 a diseased eye of a similar age are compared at increasing 

 magnifications in Figs 17-22. The lenses, composed of cu- 

 ticle, are absent in the diseased eye, and the rhabdoms 

 and associated cells are twisted, tangled masses. Also, 

 the basement membrane is absent, and only remnants of the 

 optic nerve may be seen. Pigment granules are present in 

 the pigment cells of the diseased eye. 



