320 EMBRYOLOGICAL METHODS. 



See also (for Chironomus) HITTER, Zeit. f. wiss. Zool., L,. 

 1890, p. 408; Zeit. f. wiss. Mik., viii, 1, 1891, p. 87 (strings 

 of ova fixed with hot 30 per cent, alcohol containing a little 

 sublimate, and stained in the mass by immersion for several 

 days in picro-carmine). 



621. 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. 



622. Araneina (BALFOTJE, Quart. Journ. Hie. 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. 



KISHINOUYE (Journ. Coll. Sci. Imp. Univ. Japan, iv, 1891, 

 p. 55; Zeit. f. wiss. Mik., ix, 2, 1892, p. 215) fixes in water 

 warmed to 70 or 80 C., puts into 70 per cent, alcohol, and 

 after twenty-four hours therein pierces the membranes and 

 passes through stronger alcohol. Stain with alcoholic cochi- 

 neal or picro-carmine, and imbed in paraffin. 



See also LOCY, Bull. Mus. Comp. Zool., Harvard, xii, 3, 1886 ; Zeit. f. 

 wiss. Mik., iii, 2, 1886, p. 242. Fix by hot water. The liquid of Perenyl 

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



623. 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. 



624. 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 per centi. 

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

 pierced with needles, and the ovum turned out. 



625. 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 orO'5 per cent, chromic acid, wash out for the same time in running 

 water, and bring into alcohol. Remove the chorion, remove the embryo 

 from the yolk by means of a sharp knife, and stain with picro-carmine and 

 mount in balsam. 



