392 EMBRYOLOGY 



ova segmenting right through absolute alcohol into balsam. 

 Bataillon {Arch. Entwickelungsmech., 1901, p. 149) has had ova 

 showing living embryos after having been for six months in liquid 

 of Flemming, and found them to remain alive for months after 

 drying for twenty-four hours at 35° C, and mounting in balsam, 

 and for weeks in acids or alkalies. 



Doubtless the best fixative yet made known for ova furnished 

 with their capsules will be found to be that of Carnoy and Lebrun, 

 § 91 {La Cellule, xiii, 1897, p. 68). After fixation the ova are 

 carefully brought into 80 per cent, alcohol, in which they are 

 preserved. Imbedding should be carefully done as recommended 

 for the ova of Amphibia (§ 825), but they ought not to remain in 

 the pure parafiin for more than a minute to a minute and a half. 

 But these authors prefer the celloidin method. At least six 

 weeks' soaking in the different strengths of celloidin will be neces- 

 sary to ensure penetration. They stain with iron hsematoxylin. 



ZuR Strassen {Arch. Entwickelungsmech., iii, 1896, p. 29) fixes 

 for twenty-four hours in a mixture of 4 parts 96 per cent, alcohol 

 and 1 part acetic acid, brings into pure alcohol, stains with hydro- 

 chloric acid carmine, and brings gradually into glycerin. 



Similarly Zoja {Arch. mik. Anat., xlvii, 1896, p. 218) and 

 Erlanger {ibid., xlix, 1897, p. 309). Zoja stained with Bismarck 

 brown and examined in dilute glycerin ; Erlanger made paraffin 

 sections and stained with iron hsematoxylin. 



KosTANECKi and Siedlecki {ihid., xlviii, 1896, p. 184) employed 

 concentrated sublimate solution, or 3 per cent, nitric acid or 

 mixtures of these two, for ovarian ova. 



Van Beneden and Neyt {Bull. Acad. Belg., 1887, p. 214) 

 took equal parts of alcohol and acetic acid. Boveri {Jena Zeit., 

 xxi, 1887, p. 423) fixed in his picro-acetic acid, § 100 — a clearly 

 inadequate method. Gulick {Arch. Zellforsch., vi, 1911) has 

 " fixed " ova of Heterakis for twenty-two hours in one-third 

 saturated picric acid with 3 per cent, of glacial acetic acid, and 

 had them develop in alcohol of 70 per cent, to stages representing 

 a normal development of several weeks. 



Boring {Arch. Zellforsch., iv, 1909, p. 121) spreads ova of 

 Ascaris on a layer of Mayer's albumen on a slide, sets the albumen 

 with a drop of formol, fixes with 4 parts of alcohol to 1 of acetic 

 acid, stains in alcoholic hydrochloric acid carmine, and mounts in 

 glycerin. 



Artom {Zeit. wiss. Mik., xxv, 1908, p. 5) freezes segments of 

 the uteri of Ascaris in salt water, and cuts them with the freezing 

 microtome into discs 30 /a thick, and fixes these with divers liquids. 

 Cerfontaine {ibid., xxix, 1912, p. 305) brings fixed ova from 

 alcohol into absolute alcohol with 1 per cent, of clove oil, 

 evaporates this down to one-tenth, puts into absolute alcohol 

 with 5 per cent, of clove oil, evaporates again down to one- 



