ASTAOUS. 273 



the fly may be fixed by plunging the animal for some tiros 

 into boiling water, then dissecting out and bringing them into 

 70 per cent, alcohol. Laid eggs may have boiling water 

 poured over them, or be put into solution of Flemming in a 

 test-tube which is plunged into boiling water until the eggs 

 begin to darken (about a minute) . Cold solution of Flemming 

 easily causes a certain vacuolisation of the contents of the ova. 

 Open the ova at the larger end, stain with borax-carmine for 

 fifteen to thirty hours, and cut in paraffin. 



586. Aphides (WILL, Semper' s Arbeiten, 1883, p. 223). Sections to 

 be made through the entire animals containing the ova and embryos. The 

 animals are killed in water of 70 C., and brought into alcohol. The cuticle 

 may then be pricked with a needle and the animals stained in the mass with 

 borax-carmine or hsematoxylin. You may imbed in collodion and collodio- 

 nise the sections as cut. 



587. Araneina (BALFOUE, Quart. Journ. Mic. Sci., 1880, p. 167). 

 Balfour hardened the embryos in bichromate of potash, after placing them 

 for a short time in nearly boiling water. After removal of the membranes 

 they were stained as a whole with hsematoxylin, and imbedded for cutting 

 in coagulated albumen. 



588. Agelena (Locr, Bull. Mus. Comp. Zool. Harvard, xii, 3, 1886 ; 

 Zeit.f. wiss. Mik., iii, 2, 1886, p. 242). Fix by heating the ova in water 

 to 80 C., and bring them into alcohol. The liquid of Perenyi may 

 also be used ; it has the advantage of not making the yolk so granular. 



589. Phalangida (BALBIANI). The ova of Phalangium opilio are en- 

 closed in a chorion covered with yellow corpuscles which renders them quite 

 opaque. They may be cleared by treating them with water containing a 

 little solution of caustic potash and raised to boiling-point. The ova are 

 then laid on blotting-paper, and the chorion is removed by rubbing them 

 gently with a small brush. The vitelline membrane remains intact and 

 transparent, and the embryo may be studied through it. 



590. Phalangida (HENKING, Zeit. f. wiss. Mik., iii, 4, 1886, pp. 470 

 et seq.). Fix with boiling water or "Flemming." Preserve the ova in 

 90 per cent, alcohol. To open the chorion, bring them back into 70 percent. 

 alcohol, which causes them to swell up so that the chorion can easily be 

 pierced with needles, and the ovum turned out. Stain with borax-carmine 

 or with " eosin-haematoxylin " (sic). Penetrate with bergamot oil (rather 

 than chloroform or toluol) and imbed in paraffin. 



591. Astacus (REICHENBACH, from Zeit.f. wiss. Mik., 1886, p. 400). 

 Fix in water gradually warmed to 60 or 70 C. (if the chorion should burst, 

 that is no evil), harden for twenty-four hours in 1 to 2 per cent, bichromate 

 of potash or 0'5 per cent, chromic acid, wash out for the same time in run- 

 ning water, and bring into alcohol. Remove the chorion, remove the em- 



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