EMfiBYOLOGIOAr, METHODS. 305 



avoid deformation of the embryos, and put tlie ova Ijack into the acid 

 for an hour. Wash oiit in 1 to 2 pei' cent, solution of alum for an 

 hour and harden in alcohol. 



Modification of this method by Goronowitsch {seeMorph. Jahrb., x, 

 1884, p. 381). 



613. Selaehia.— Beaed {Anat. Ana., xviii, 1900, p. 556) has 

 found that the best fixatives for embryos of Raja are Rabl's 

 picro-platiiiic 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. Abth., 1897, p. 3). See also 

 Bbaus, Morph: Jahrb., xxxv, 1906, p. 250. 



614. Amphioxus, — Sobotta {Arch. 7nik. Anat., 1, 1897, p. 

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

 Hatschek (^4?-&. Zool. Inst. Wien., iv, 1881) in picro-sulphuric 

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

 mentation is completed during -the night. 



Legeos {Grundzilge, Lee and Mayee, 1910, p. 288) fixes 

 ova and embryos in equal parts of formol and Flemming. 

 Sublimate is not good ; Rabl's mixtures are better. Larvas 

 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. 



Cekfontaine {Arch. 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 Pish Ova. — Whitman {Amer. Natural, xvii, 1883, pp. 

 1204-5; and Mettiods of Research, etc., p. 162). — Fix by treatment first 

 for five to ten minutes with a mixture of equal parts of sea-water and 

 5 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. Nut. Hist., x, 

 1892, p. 228. 



Raffaelb {Mittli. 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). 



Hbinkb and Ehkenbaum {Wiss. Meeresunt. Komm. Wiss. Unt. D. 



20 



