126 MAINK AGKlCUI.TURAr, KXI'KRl M l- X T S'I'ATlOX. I9O3. 



TECHNIQUE. 



The mattM-ial was fixed with hot water. alcohoHc-picro- 

 sulphuric. and alcoholic picro-corrosivc acetic. The two latter 

 solutions wlu'ii used hot gave the best histological results. Some 

 eggs in the earlier stages which were fixed in absolute alcohol 

 gave very satisfactory results. In all cases the material was 

 washed immediately after killing in 70 per cent alcohol. 



In studying the different stages as entire transparent objects 

 the best results were obtained by pricking each specimen with a 

 very fine needle, and staining either in Grenacher's borax-car- 

 mine or alcoholic cochineal for twenty-four to forty-eight hours. 

 Then the material was Avashed with yo per cent alcohol acidulated 

 with a few drops of hydrochloric acid for two or three days, or 

 until it was bleached sufficiently. Xylol was used for the clear- 

 ing medium as it gave whiter and more transparent mounts than 

 either clove or cedar oil. 



In sectioning the younger stages, Dr. Drew's method for orien - 

 ing small objects was very helpful.* The eggs to be sec 

 tioned were stained as for whole mounts, but were not washed 

 out as thoroughly. They were then cleared in clove oil, mounted 

 on the tracing cloth and finally cleared in xylol before trans- 

 ferring them to the paraffin bath. By this method good series 

 of sections were obtained of all the stages. The sections were 

 finally stained on the slide with Mayer's haemalum or iron 

 haematoxylin. 



EMBRYOLOGY. 



The surface of the eggs is smooth and without any markings. 

 When newly laid they are creamy white or very light green, but 

 in two or three days they become darker, growing almost black 

 before the time of hatching. The color change starts from the 

 pointed end of the egg and extends over the surface. As will 

 be seen from Figs. 41, 44 and 48, the eggs are elongated oval, 

 one side being a little concave. The body of the egg is from 

 .2 to .25 millimeters in length, and from .085 to .1 millimeter in 

 diameter through the thickest part. A short narrow stalk at the 



*Drew, Gilruan A. A modiflcation of Patten's method of irnberiding smaU 

 objects for sectioning In definite planes. Zoologischen Anzeiger, Bd. XXIII, No. 



en. 1900. 



