EMBRYOLOGICAL METHODS. 291 



STRASSEE, ibid., iii, 1880, p. 179, and iv, pp. 168 and 330 ; KASTSCHENKO, 

 ibid., iv, 1887, pp. 235-6 and 353, and v, 1888, p. 173; SCHAPER, ibid., 

 xiii, 1897, p. 446; ALEXANDER, ibid., p. 334, and xv, 1899, p. 446; 

 PETER, ibid., xxii, 1906, p. 530; BORN and PETER, ibid., xv, 1, p. 31 ; 

 and Verh. Anat. Ges., xiii, 1899, p. 134 ; JOHNSTON, Anat. Anz., xvi, 

 1899, p. 261 ; FOL, Lehrb., p. 35 or previous editions ; BROMAN, Anat. 

 Hefte, xi, 1899, p. 557 ; PETER, " Die Methoden d. Rekonstruction " 

 (Fischer, Jena, 1906); SCHONEMANN, Anat. Hefte, xviii, 1901, p. 117; 

 GAGE, Anat. Record, i, 1907, p. 167 ; NEUMAYER, Festschr. f. Kupffer, 

 1899, p. 459 ; MARK, Proc. Amer. Acad. Sci., xiii, 1907, p. 629 (electric 

 \vax-cutter for cutting out plates). 



HILL (Still. Johns Hopkins Hosp., xvii, 1906, p. 114) finds that embryos 

 of mammalia taken from 95 per cent, alcohol and put into caustic potash 

 of 1 per cent, become so transparent that they can be studied without 

 cutting and reconstructing. 



Mammalia. 



591. Rabbit Dissection. For the study of the early stages 

 the ova must be sought for in the tubse a certain number of 

 hours after copulation. The dehiscence of the follicles takes 

 place about ten hours after the first coitus. The ttibre and 

 cornua having been dissected out should be allowed to cool, 

 and remain until the muscular contractions have ceased. 

 Then, with the aid of fine scissors or a good scalpel, all the 

 folds of the genital duct are carefully freed from their 

 peritoneal investment. 



The tubas are then (if the ova are still within them, which 

 is the case up to the end of the third day after coition) laid 

 out on a long slip of glass, and slit up longitudinally by means 

 of a pair of fine, sharp scissors. By means of needles and 

 forceps the tubal mucosa is spread out so as to smooth out 

 its folds as much as possible, and is carefully looked over 

 with a strong lens or with a lower power of the microscope. 

 When the ova are found, a drop of some " indifferent " liquid 

 is dropped on each, and it is carefully taken up with the 

 point of a scalpel, a cataract needle, or a small pipette. They 

 may be examined in the peritoneal fluid of the mother if the 

 animal has been killed, or in its aqueous humour, or in 

 amniotic liquid, or in blood-serum, or in KRONECKER'S or 

 other artificial serum. 



If you have not been able to find the ova with the lens or 

 the microscope, scrape off the epithelium of the tubal mucosa 

 with a small scalpel, mix it with a little indifferent liquid, 



