386 EMBRYOLOGY 



acid or concentrated sublimate. Advanced embryos are first 

 got into extension by means of 2 per cent, cocaine, or are rapidly 

 killed with hot sublimate. 



Schmidt {Entw. Pulmonaten, Dorpat, 1891, p. 4) fixes the ova 

 in toto with concentrated sublimate, and dissects them out after- 

 wards. 



Similarly Kofoid {Bull. Mus. Harvard Coll., xxvii, 1895, p. 35). 

 Or, preferably, the ova are put into salt solution, the shell removed, 

 the albumen removed with a pipette full of salt solution, which 

 dissolves it ; the ova are then fixed for one minute in Fol's modi- 

 fication of liquid of Flemming, and brought direct into Orth's 

 picro-lithium-carmine. See also Linville, ibid., 1900, p. 215, 

 who adopts this method of shelling, but prefers fixing in acetic- 

 acid sublimate, or liquid of Perenyi. 



Heyder {Zeit. wiss. Zool., xciii, 1909, p. 92), before imbedding 

 embryos of Arion that have been fixed with sublimate, treats 

 them for an hour or two with carbonate of soda of ^ to jV per 

 cent., which makes the stomach and intestine less brittle. 



Gatenby {Quart. Journ. Micr. Science, 1919), for Limnwa 

 stagnalis ova, used Flemming's strong fluid without acetic acid, 

 Champy's fluid for two days to a week, and Kopsch's method. 



Holmes {Journ. of Morph., 1900, p. 371) teases the egg-capsules of 

 Planorbis in nitrate of silver of | per cent., exposes to sunlight until the 

 cell-limits come out, rinses with 0-2 per cent, hyposulphite of soda, 

 puts for a few minutes into picric acid, and then through alcohol into 

 balsam. 



See also Washburn, Amer. Anat., xxviii, 1894, p. 528 (liquid of Flem- 

 ming, or 0-3 per cent, chromic acid, or 1 per cent, osmic acid, followed 

 by liquid of Merkel). 



CoNKLiN {Journ. of Morph., xiii, 1897, p. 7) fixes ova of Crepidula for 

 fifteen to thirty minutes in picro-sulphuric acid, and stains with dilute 

 acidified haematoxylin of Delafleld. 



KosTANECKi and Wierzejski {Arch. mik. Anat., xlvii, 1896, 

 p. 313) fix the spawn' of Physa fontinalis either in 1^ to 2 per 

 cent, nitric acid, or in " sublimate and 3 per cent, nitric acid in 

 the proportion of 2 : 1," and bring through successive alcohols. 

 They imbed entire ova in paraffin, but isolated embryos in celloidin. 



844. Chiton, see Metcalf, Stud. Biol. Lab. Johns Hopkins Univ., v, 

 1893, p. 251. (Ova with young embryos put for twenty to forty-five 

 seconds into eau de Labarraque, then into water, in which the chorion 

 swells and can easily be removed.) 



845. Lamellibranchiata. Stauffacher (Jena Ze27., xxviii, 1893, 

 p. 196) fixes embryos of Cyclas in sublimate, stains with haemalum, 

 and cuts in paraffin. 



Lillie {Journ. of Morph., x, 1895, p. 7) fixes ova of Unio for 

 ten to twenty minutes in liquid of Perenyi, and preserves them 

 in 70 per cent, alcohol, or advanced embryos with liquid of Merkel 



