286 EMBRYOLOGICAL METHODS. 



larvae of Pkalacrocera. He could not succeed in softening the chitin 

 with eau de Javelle. 



PEREZ (Arch. Zool exper., (4), v, 1910, p. 11) fixes pupae in Bouin's 

 picro-formol, or Marchoux's mixture, for twenty-four hours. 



627. Lepidoptera (BOBRETZKY, Zeit. wiss. Zool., 1879, p. 198). 

 -Ova are slightly warmed in water and .put for sixteen to twenty 



hours in 0*5 per cent, chromic acid. The membranes can then be 

 removed. 



628. Hymenoptera. CARRIERE and BURGER (Nova Acta Acad. 

 Leop. Car., Ixix, 1897, p. 273) kill ova of Chalicodoma by warming 

 in water to 60 C., and fix in aqueous picric acid, or alcohol of 

 70 per cent". 



PETRUNKEWITSCH (Zool. Jahrb., Abth. Morph., xiv, 1901, p. 576) 

 fixes for twenty-four hours in his sublimate mixture, and passes 

 into alcohol of 70 per cent, with iodine. 



629. Orthoptera (PATTEN, Quart. Journ. Mic. Sci., 1884, p. 549).- 

 The ova or larvae (of Blattida) are placed in cold water, which is 

 gradually raised to 80 C. You leave off heating as soon as the ova 

 have become hard and white. Pass very gradually through succes- 

 sive alcohols, beginning with 20 per cent. 



WHEELER (Journ. of Morph., iii, 1889, p. 292) dissects out ovarian 

 ova in salt solution and fixes in liquid of Perenyi (fifteen minutes), 

 then treats with alcohol, and stains with borax-carmine. Laid 

 eggs may be killed by Patten's method. After heating, the two 

 lips of the crista of the capsule may be separated with fine forceps 

 and pieces of the walls torn away, and the eggs pushed out of the 

 compartments formed by their choria and hardened as desired. 

 Good results are also obtained by heating to 80 C. for ten minutes 

 in liquid of Kleinenberg, and preserving in 70 per cent, alcohol. 

 This causes the envelopes to dilate and stand off from the surface of 

 the egg, so that they can easily be dissected away. 



HEYMONS (Zeit. wiss. Zool., liii, 1892, p. 434), for young embryos, 

 incises the cocoon at the end by which it adheres in the body of the 

 mother, brings it for two minutes into water heated to 90 C., and 

 opens in Flemming, in which the embryo is dissected out. 



MORGAN (Amer. Natural., xxii, 1888, p. 357) puts ova of Peri- 

 planeta for thirty minutes or an hour into eau de Javelle diluted with 

 4 to 8 volumes of water and slightly warmed, which softens the 

 capsules. 



630. Coleoptera. HIRSCHLER (Zeit. wiss. Zool., xcii, 1909, p. 628) 

 fixes ova of Donacia (after incising the chorion) for two to three 



