74 Frederick H. Krecker, 



Targioni-Tozzetti (68), says, the male has four simple eyes 

 composed of a convex Cornea and a transparent, spherical, crystalline 

 body wliich is surrounded by a great mass of brown, violaceous, almost 

 black, fairly definitely arranged pigment. He found no nervous con- 

 nection between the eye and the cerebral ganglion. Instead of the 

 condition just described he states that the last nymphal stage had 

 two, large undivided pigmented masses which later separated and 

 assumed an ovoid form. Because of this last Statement and of the 

 fact that he gives the number of eyes as four this description must 

 apply only to the so-called accessory eyes. 



In addition to the accessory eyes, Berelese (93), also describes 

 the lateral eyes. For botli he gives much the same description as does 

 Targioni, although with more detail. Furthermore he fomid a nerve 

 running from the eye to the supraoesophageal ganglion. In regard to 

 the latter eyes he states that the pigment is in layers perpendicular 

 to the plane of the cornea. 



Before going further a word as to technique might not be out of 

 place. It was most convenient to prepare the entire insect. Specimens 

 were obtained representing the various developmental as well as the 

 adult stages of the eyes. These were placed in small vials in which 

 they were kept until embedded, thus saving considerable time and 

 all unnecessary handling. In the choice of a fixative there was con- 

 sidered ability to penetrate the thin waxy secretion and to prevent 

 shrinkage of the tissue, rec|uirements that were best fulfilled by Gilson's 

 Sublimate Solution heated, although hot absolute alcohol also proved 

 good. With these fixatives Delafield's hematoxyiin counterstained 

 w^th eosin proved the most satisfactory. Bleu de Lyon with borax 

 carmin did not yield the results obtained by Redikorzew. A short 

 immersion in acid alcohol immediately after Bleu de Lyon intensified 

 the stain. Sections on the slide were stained well by borax carmin 

 in 4 — 5 hours. Flemming's Solution could not be relied upon for 

 thorough Penetration of the tissue. With this fixation iron hematoxyiin 

 brought out details clearly, as usual. Cedar oil was used for Clear- 

 ing. The sections, for the most part, were cut 3 mica thick, a few 5. 

 Depigmenting was done on the slide according to Mayer's Chlorine 

 Method. 



Because of the minuteness of the eyes maceration preparations 

 were entirely out of the question. Consequently the only possible 

 method of study was by means of sections taken through the head, a 

 method which in certain respects is unsatisfactory. Some difficulty 



