EMUKYOUMiK'AI, METHODS. o05 



avoid deformation of the embryos, and put the ova back into the acid 

 for an hour. Wash out in 1 to 2 per cent, solution of alum for an 

 hour and harden in alcohol. 



Modification of this method by GOUONOWITSCH (see Morph. Jahrb., x, 

 1884, p. 381). 



613> Selachia. BEARD (Anat. Anz., xviii, 1900, p. 556) has 

 found that the best fixatives for embryos of Raja are RabPs 

 picro-platinic mixture, 587 and sublimate. 



Living embryos can be observed by scraping the shell thin 

 with a knife (KASTSCHENKO, Anat. Anz,, iii, 1888, p. 445, and 

 His, Arch. Anat. Phys. Anat. AbtJi., 1897, p. 3). See also 

 BKAUS, Morpli. Jahrb., xxxv, 1906, p. 250. 



614. Amphioxus. SOBOTTA (Arch, mil-. Anat.,, 1, 1897,, p. 

 20) fixes for twenty-four hours in liquid of Flemming ; 

 HATSCHEK (Arb. Zool. lust. Wien., iv, 1881) in picro-sulphuric 

 acid. Impregnation takes place in the evening, and seg- 

 mentation is completed during the night. 



LEOROS (Grnndziige, LEU and MAYER, 1910, p. 288) fixes 

 ova and embryos in equal parts of formol and Flemming. 

 Sublimate is not good ; RabPs mixtures are better. Larvae 

 and young animals ought first to be ana3sthetised with 

 cocain in sea-water. After fixation they should remain only 

 for as short a time as possible in alcohol. 



CfcUiFONTAiNE (Arcli . Biol., xxii, 1906, p. 287) fixes with 

 Flemming or Hermann. For study of ova in toto he orients 

 them on a slide in clove-oil-collodion which he sets with 

 chloroform, and adds balsam. For sectioning, he orients in 

 the same way on a layer of paraffin spread on a cover glass, 

 and imbeds the whole in paraffin. 



615. Pelagic Fish Ova. WHITMAN (Amer. Natural, xvii, 1883, pp. 

 1204-5; 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 P 25 per cent, platinum chloride 

 and 1 per cent, chromic acid. Prick the membrane before transferring 

 to alcohol. See also AGASSIZ and WHITMAN, uiProc. Amer. Acad. Arts 

 and Sciences, xx, 1884; and COLLINGE, Ann. and Mag. Nat. Hint., x, 

 1892, p. 228. 



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 EHKENBAUM (Wins. Meeresunt. Komm. Wiss. Unt. D. 



20 



