EMBRYOLOGTCAL METHODS. 353 



branes and passes through stronger alcohol. Stain with 

 alcoholic cochineal 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 Perenyi 

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



632. Scorpionidea. BRAUEK (Zeit.f. wiss. Zool., Ivii, 1894, 

 p. 405) removes ovarian tubes from living Euscorpius, and 

 fixes the small ova for half an hour to an hour in liquid of 

 Flemming, then dissects out the ova. He puts tubes with 

 more advanced embryos for twenty-four hours into one fifth 

 per cent, chromic acid, or for a minute to a minute and a 

 half into almost boiling water, and then for two to six hours 

 into chromo-acetic acid, or for ten to twenty minutes into 

 liquid of Flemming. The chromic acid material is only good 

 for surface views. 



633. Tardigrada. ERLAXGEE (Morph. Jahrb., xxii, 1895, p. 493) fixes 

 the ova (and the animals themselves) in liquid of Flemming or in picro- 

 sulphuric acid containing 1 drop of 1 per cent, osmic acid per c.c., or in 

 concentrated sublimate solution with 20 per cent, acetic acid. The two first 

 require to be bleached with warm peroxide of hydrogen. 



634. Limulus. KINGSLEY (Journ. of Morph., vii, 1892, p. 38) 

 warms the ova in sea water to 70 or 75 C., and then brings 

 them into alcohol of 30 to 70 per cent. For early stages he 

 marks the position of the embryo with Indian ink on the 

 chorion ; the mark resists alcohol. Early stages should be 

 imbedded in celloidin, later ones in paraffin. For the pre- 

 paration of surface views see op. cit., xii, 1896, p. 23. 



Similarly KISHINOUYE, Joum. Coll. Sc. Japan, v, 1893, 

 p. 56. 



635. Astacus (REICHENBACH, Abk. Senckenberg. Ges. Frank- 

 furt, xiv, 1886, p. 2; 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 running water, 

 and bring into alcohol. Remove the chorion, and remove 

 the embryo from the yolk by means of a sharp knife. 



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