346 CHAPTER XXVI. 



612, Selachii SCHMIDT'S Method (see Zeit.f.wiss.Mik., xv, 3, 1899, 

 p. 332). Fix in acetic sublimate. 



613. Pelagic Fish Ova WHITMAN'S Method (Amer. Natural., xvii, 

 1883, pp. 1204-5 ; Journ. Roy. Mic. Soc. [N. S.], iii, 1883, p. 912 ; and 

 Methods of Research, etc., p. 152). Fix by treatment first for five to ten 

 minutes with a mixture of equal parts of sea water and \ per cent, osmic 

 acid solution, and then for one or two days with a solution (due to Eisig) 

 of equal parts of 0'25 per cent, platinum chloride and 1 per cent, chromic 

 acid. Prick the membrane before transferring to alcohol. See also AGASSIZ 

 and WHITMAN, in Proc. Amer. Acad. Arts and Sciences, xx, 1884; and 

 COLLINGE, Ann. and Mag. Nat. Hist., x, 1892, p. 228; Journ. Roy. Mic. 

 Soc., 1892, p. 883. 



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

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

 alcohol 1, acetic acid 1, saturated sublimate solution in water 2). 



614. Amphioxus. SOBOTTA (Arch. mik. Anat., I, 1897, p. 

 20) advises fixing- for twenty-four hours in liquid of 

 Flemming. 



Tunicata. 



615. Ova. DAVIDOFP (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. The ova to remain in it for from half an hour 

 to an hour, and be then washed for a few minutes in water 

 and brought through successive alcohols. Another reagent, 

 almost as good, consists of 3 parts of saturated solution of 

 picric acid and 1 of glacial acetic acid, the objects to remain 

 in it for three to four hours, and then be brought into 70 per 

 cent, alcohol. 



CASTLE (Bull. Mus. Harvard Coll., xxvii, 1896, p. 213) advises for ova 

 of Cioiia liquid of Perenyi for twenty minutes, followed by 70 per cent, 

 alcohol for twenty-four hours, and for the larvae picro-nitric acid. 



616. Test-Cells of Aseidians (MORGAN, Journ. of Morplwi., iv, 1890, 

 p. 195). Tease fresh ovaries in veiy 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 demonstrated. 



617. Buds. PIZON (Ann. Sc. Nat., xix, 1893, p. 5) studies 

 the gemmation of the composite Aseidians either on entire 



