364 F. M. BALPOtJR ON DEVELOPMENT OF THE DOG-FISH. 



near its distal extremity, another branch, the superior 

 maxillary branch. 



In its embryonic condition this latter branch does not 

 appear like a third branch of the fifth, equivalent to the 

 seventh or the gldsso-pharyngeal nerves, but rather resembles 

 the branch of the seventh nerve which passes to the arch in 

 front, which also is present in all the other cranial nerves. 



Modes of Preparation. 



Before concluding I will say one or two words as to my 

 modes of preparation. 



I have used picric and chromic acids, both applied in the 

 usual way ; but for the early stages I have found osmic acid 

 by far the most useful reagent. I placed the object to be 

 hardened, in osmic acid (half per cent.) for two hours and a 

 half, and then for twenty- four hours in absolute alcohol. 



I then embedded and cut sections of it in the usual way, 

 without staining further. 



I found it advantageous to cut sections of these embryos 

 immediately after hardening, since if kept for long in the 

 absolute alcohol the osmic acid specimens are apt to become 

 brittle. 



List of Works referred to. 



Gegenbaur. — ' Anat. der Wirbelthiere,' III Heft, Leipzig, 1873. 

 A. Gdtte.—' Archiv. fiir Micr. Anat.,' vol. x, 1873. 



„ " Der Keim der forelleneies," ' Archiv. fiir Micr. Anat.,' vol. ix, 



1873. 

 „ " Untersuchung iiber die Entwickelung der Bombinator igueus,'' 



' Archiv. fiir Micr. Anat./ vol. v, 1869. 

 „ " Kurze Mittheilungen aus der Entwicklungseeschichte der 

 Unke," ' Archiv. fiir Micr. Anat.,' vol. ix, 1873. 

 Kupffer.—'kxc\i\v. fiir Micr. Anat.,' vol. ii, 1866, p. 473. 



Ibid., vol. iv,] 868, p. 209. 

 Kowaleviky. — " Entwickelungs^eschichte der Holothurien," ' Memoirs de 

 I'Acad. Imper. des Sciences de St. Petersbourg,' vii 

 ser., vol. xi, 1867. 

 KcmaUvshy, Owsjannikow, und Wagner. — " Entwickelung der Store," ' Bul- 

 letin der K. Acad. St. Petersbourg,' vol. xiv, 1873. 

 Eowaleosky. — ^ " Embryologische Studien au Wurmern und Arthropoden," 

 ' Memoirs de I'Acad. Imper. des Sciences de St. Peters- 

 bourg,' vol. xvi, 1871. 

 E. 'Ray Lankester, 'Annals and Mag. of Nat. History,' vol. xi, 1873, p. 81. 

 W. Miiller. — " Uber die Persistenz der Urniere bei Myxine Glutinosa,' 



' Jenaische Zeitschrift,' vol. vii, 1873. 

 Oellacher. — * Zeitschrift fiir Wiss. Zoologie,' vol. xxiii, 1873. 

 Owsjannikow. — " Entwickelung der Coregonus," * Bui. der K. Akad. St. 



Petersbourg,' vol. xix. 

 Romiti. — ' Archiv. fiir Micr. Anat.,' vol. ix, 1873. 

 Waldeyer.—' Eierstock u. Eie.' 



