384 EMBRYOLOGY 



Raffaele (Mitth. Zool. Stat. Neapel, xii, 1895, p. 169) fixes chiefly 

 with liquid of Hermann (1 to 2 days), or with a mixture of Mingazzini 

 (absolute alcohol 1, acetic acid 1, saturated sublimate solution in 

 water 2). 



Heinke and Ehrenbaum {Wiss. Meeresunt. Komm. Wiss. Unt. D. 

 Meere, iii, Heligoland, 1900, pp. 205 and 213) prefer formol with 39 

 volumes of sea-water. 



TUNICATA 



838. Ova. Davidoff (Mitth. Zool. Stat. Neapel, ix, 1, 1889, 

 p. 118) fixes the ova of Distaplia with a mixture of 3 parts of 

 saturated solution of corrosive sublimate and 1 of glacial acetic 

 acid for from half an hour to an hour ; or with a mixture of 

 3 parts of saturated solution of picric acid and 1 of glacial acetic 

 acid for three to four hours ; then 70 per cent, alcohol. 



Castle {Bull. Mus. Harvard Coll., xxvii, 1896, p. 213) advises 

 for ova of Ciona liquid of Perenyi for twenty minutes, followed 

 by 70 per cent, alcohol for twenty-four hours, and for the larvae 

 picro-nitric acid. 



839. Test-Cells of Ascidians (Morgan, Journ. of MorphoL, iv, 1890, 

 p. 195). — Tease fresh ovaries in very weak osmic acid, wash in distilled 

 water, treat for half an hour with 1 per cent, silver nitrate, wash for 

 half an hour in 2 per cent, acetic acid and reduce in sunlight. Imbed 

 in paraffin. By this process the limits of the follicle cells are demon- 

 strated. 



840. Buds. PizoN (Ann. Sc. Nat., xix, 1893, p. 5) studies the 

 gemmation of the composite Ascidians either on entire corms, 

 which he first bleaches with peroxide of hydrogen and then 

 stains, or by making sections, after anaesthetising the colonies 

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

 sulphuric or liquid of Flemming, and staining m 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). 



RiTTER (Journ. of Morph., xii, 1896, p. 150) recommends for 

 fixing Perophora and Goodsiria picro-sulphuric acid. 



BRYOZOA 



841. Statoblasts. Braem (Bihl. Zool. Chun and Leuckart, 

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

 centrated 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 



842. Cephalopoda (Ussow, Arch, de Biol., ii, 1881, p. 582). 

 Segmenting ova are placed in 2 per cent, solution of chromic 



