NERVOUS SYSTEM OF SCORPION. 



39 



ch. 







-n* 



to keep them m a separate vial. The embryos may be studied 

 in alcohol, but for cleared preparations the following process was 

 found to give good results : The yolk was removed with needles 

 and fine brushes and the embryos were then stained in Delafield's 

 haematoxylin, diluted with water acidulated 

 with a trace of picro-sulphuric, dehydrated 

 with alcohols acidulated with the same and 

 mounted in balsam. The intensity of the 

 stain must be controlled by the proportions 

 of the stain and acid used, and the time they 

 are allowed to act. Eggs for sectioning were 

 imbedded in paraffin and the block cut so as 

 to remove as much of the yolk as possible 

 without injury to the parts desired, then re- 

 imbedded and sectioned and stained in Hei- 

 denhain's iron-haematoxylin. It is difficult, 

 even with the use of the mastic-collodion pro- 

 cess, to obtain perfect series of the entire 

 egg. Embryos ready to hatch could be to 

 some extent dissected, but contained a large 

 amount of yolk. 



cida drawing of the 



Adults for dissection were opened while right side O f a cleared 

 fresh and the blood washed out and liver surface preparation of 

 partly removed in physiological salt solution, the embryo of Cen- 



, . , ill A i 1, r trurioides vittattis as 



then hardened in weak alcohol. Adults for 



early as the neurome- 



sectioning were taken immediately after moult- res are clearly distin- 

 ing and injected with Flemming's fluid, in guishable, >( 45. ch, 



which they were left six days, followed by 'helicera; *I-T, first 



to seventh neurome- 

 pyroligneous acid (v. Mahrenthal), or pyro- res . 0> mout h. 



gallic acid (Hermann) for two or three days ; 

 or they were stained with Heidenhain's iron hasmatoxylin after 

 any good fixative. This latter process brings out the nerve- 

 fiber tracts in the fibrous substance of the nerve center. In 

 staining on the slide, parts of sections were often washed off, 

 though they had been attached with Meyer's albumen fixative, 

 flattened with the aid of warm water, and dried for twenty-four 

 hours. To prevent this I took the slides after drying and 

 painted them with three fourths per cent, celloidin (Gage) and 



FIG. I. Camera lu- 



