332 CHAPTER XXVI. 



embryos (Pisces, Amphibia, Aves, Mammalia). Advanced 

 embryos of Teleostea ought to be fixed in the warmed mix- 

 ture, in order to avoid rupture of the muscles and shrinkage 

 .of the chorda. 



RAUL'S picro-sublimate mixture has been given 61. It 

 is recommended especially for somewhat advanced embryos, 

 such as embryo chicks from the third or fourth day, and 

 other embryos of a similar size. 



BOVERI (Verh. Physik. Med. G-es. Wiirzburg, xxix, 1895, 

 p. 4), in order to imbed and cut together numbers of ova of 

 Echinoderms, wraps them in pieces of sloughed epidermis of 

 Cryptobranchus (of course other Urodela will do). SOBOTTA 

 (Arch. f. mik. Anat., 1, 1897, p. 31) takes pieces of amnios 

 of Mammalia. 



588. Reconstruction of Embryos from Sections. The study of 

 a series of sections of any highly differentiated organism is 

 so complicated that it is often necessary to have recourse to 

 elaborate methods of geometrical or of plastic reconstruction 

 in order to obtain an idea or a model of the whole. These 

 methods ha,ve now been brought to so high a degree of com- 

 plexity that a volume rather than a paragraph would be 

 necessary to describe them. See BOKN, " Die Plattenmodel- 

 lirmethode," in Arch. f. mik. Anat., 1883, p. 591, and Zeit. 

 f. wiss. Mik., v, 4, 1888, p. 433; STKASSKR, in Zeit. f. wiss. 

 Mik., iii, L>, 1886, p. 179, and iv, 2 and 3, pp. 168 and 830; 

 KASTSCHENKO, in Zeit. f. wis*. Mik., iv, 2 and 3, 1887, pp. 

 235-f> and 353, and v, 2, 1888, p. 173; SCHAPEK (ibid., 

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

 p. 446; BORN and PKTER, ibid., xv, 1, p. 31 ; JOHNSTON, 

 Anat. Anz., xvi, 1899, p. 261. For a method of FOL (Lehrb., 

 p. 35) see previous editions. 



In simple cases it may be sufficient to adopt the plan 

 described by SCHAFFER (Zeit.f. wiss. Mik., vii, 3, 1890, p. 342). 

 Careful outlines of the sections to be reconstructed are drawn 

 on tracing-paper with the aid of the camera lucida, super- 

 posed, and held up against the light for examination by 

 transparence. YOSMAER (Anat. Anz., xvi, 1899, p. 269) 

 draws on plates of celluloid, and sets them up in a rack for 

 examination. 



A method for simple graphic reconstructions without 



