EMBRYOLOGIOAL METHODS. 347 



conns, which he first bleaches with peroxide of hydrogen 

 (which acts less brutally than eau de Javelle, but the bubbles 

 that arise must be removed with an air pump), and then 

 stains ; or by making sections, after anaesthetising the colonies 

 with cocain of 1 : 1000, fixing in glacial acetic acid or picro- 

 sulphuric or liquid of Flemming, and staining in toto with 

 borax carmine or alum carmine, or with a strong solution of 

 methylen blue in alcohol of 90 or 100 per cent, (after BERNARD, 

 ibid., ix, 1890, p. 97). 



HITTER (Joum. of Morph., xii, 1896, p. 150) recommends 

 for fixing Perophora and Goodsiria picro-sulphuric acid. 



Bryozoa. 



618. Statoblasts. BRA EM (Bibl. ZooL, Chun and Leuckart, 

 6 Heft, 1890, p. 95) fixes statoblasts of Cristatella with hot 

 concentrated solution of sublimate for ten minutes, brings 

 them into water and there incises them with a razor, and 

 after half an hour passes them gradually into alcohol. He 

 stains with picro-carmine. 



Mollusca. 



619. Cephalopoda (Ussow, Arch, de BioL, ii, 1881, p. 582). 

 Segmenting ova are placed, without removal of the mem- 

 branes, in 2 per cent, solution of chromic acid for two 

 minutes, and then in distilled water, to which a little acetic 

 acid (one drop to a watch-glassful) has been added, for two 

 minutes. If an incision be now made into the egg-mem- 

 brane the yolk flows away and the blastoderm remains ; if 

 any yolk still cling to it, it may be removed by pouring 

 away the water and adding more. 



WATASE (Joum. of MorphoL, iv, 1891, p. 249; Journ. 

 Roy. Mic. Soc., 1892, p. 152) kills the ova in the macerating 

 mixture of the Hertwigs ( 538), and as soon as the 

 blastoderm turns white and opaque removes it under dilute 

 glycerin. Treatment with liquid of Perenyi is recommended 

 for surface views. 



VIALLETON (Ann. Sc. Nat., vi, 1887, p. 168) brings 

 ovarian ova of Sepia into a freshly-prepared mixture of 



