308 CHAPTER XXV. 



coagulated. The egg is opened with needles, the albumen 

 comes away in bits, and the embryo can be removed. 



Henchman [Bull. Mus. Comp. Zool., Harvard, xx, 1890, 

 p. 171) fixes ova of Limax with 0'33 per cent, chromic acid, 

 or with liquid of Perenyi. It is best to remove only the 

 outer envelope before putting into the chromic acid, the 

 inner membrane being removed after two or three minutes 

 therein. Where Perenyi is used the membranes must be 

 removed first, as the albumen will else coagulate in such a 

 way as to prevent the removal of the embryos. 



Meisenheimer [Zeit. tciss. Zool., Lxii, 1896, p. 417) dissects 

 out the embryos of Limax and fixes them with picro-sulphuric 

 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 {Enkw. Pulmonaten, Dorpat, 1891, p. 4) fixes the 

 ova ill toto with concentrated sublimate, and dissects them 

 out afterwards. 



Similarly Koeoid [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 FoFs modification of liquid of Flemming, 

 and brought direct into Orth's picro-lithum-carmine. See 

 also LiNViLLE, ibid., 1900, p. 215, who adopts this method of 

 shelling, but prefers fixing in acetic-acid-sublima,te, or liquid 

 of Perenyi. 



Heydeu (Zeit. iviss. Zool., xciii, 1909, p. 92), before imbed- 

 ding embryos of Arion that have been fixed with sublimate, 

 treats them for an hour or two with carbonate of soda of one 

 tenth to one fifteenth per cent., which makes the stomach 

 and intestine less brittle. 



Holmes (Jourv. o/Jforjj/t., 1900, p. 371) teases the egg-capsules of Ptoi- 

 orbin in nitrate of silver of f 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 thi-ough alcohol into balsam. 



See also Washbukn, A7ner. Anat., xxviii, 1894, p. 628 (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) fixs ova of Crepidula for 

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

 acidified ha;matoxylin of Delafield. 



