418 ANATOMICAL TECHNOLOGY. 



1090. Preservation. Place the preparation in the 62-67 per 

 cent, alcohol for at least two days. Then transfer it to 95 per cent, 

 alcohol, where it should remain if a permanent preparation is to be 

 made. For most purposes it is best to leave the brain supported by 

 part of the cranium. If the base of the brain is to be specially 

 studied, the base of the skull must be more completely removed ; 

 it is thin, but so closely in contact with the brain that much care is 

 required. 



1091. Labeling. To the vial containing the brain should be affixed a tag ( 162) 

 bearing the name of the genus and, if possible, of the species, and stating the sex and 

 locality of the animal, the date of the preparation, and the name of the preparator. 



The genus will be either Menobranchus (sometimes called Necturus), Rana (frog), or 

 Bnfo (toad). Probably there is only a single species of Menobranchus, lateralis, but the 

 doubt upon this point renders the noting of the locality essential. Of the toad there is 

 but one species, lentiginosus (Americana}, common in the Northern United States. There 

 are several species of frogs, the largest being the pipiens of some authors, but the Catesbi- 

 ann according to Jordan's " Manual " (A, 188). 



If any generalizations are to be based upon the specific characters of the brain, and 

 there is doubt respecting the determination, the entire body should be kept for reference, 

 and labeled like the brain. 



With the female Menobranchus the vent is a simple longitudinal slit, but with the 

 male it presents numerous papillae, especially in the spring. If in doubt, open the abdo- 

 men and note that the testes are elongated solid organs, while the ovaries are thin walled 

 sacs, one on each side, with ova of two or more sizes, the largest in the spring being yel-" 

 low and nearly as large as small peas. With frogs and toads the testes are small oval 

 bodies, while the ovaries are voluminous laminae with dark colored eggs. 



1092. General Inspection of the Amphibian Brain. In what 

 follows, including the dissection of the brain, no attempt is made to 

 give exhaustive descriptions or directions. 



Notwithstanding the numerous figures and descriptions of the frog's brain, none of its 

 parts are known as they should be, and that of Menobranchus can hardly be said to be 

 known at all excepting in the most general way. But our ignorance of many details of 

 their anatomy need not prevent our use of them for the sake of illustrating certain features 

 of brain construction which are comparatively obvious with them, but obscured with the 

 brains of the higher Vertebrates. 



Since the frog is the more common and likely to be used more frequently, the directions 

 apply primarily to it, while the peculiarities of Menobranchus are separately mentioned. 



1093. Frogs' brains are figured and more or less fully described in the following 

 works and papers. So far as we can judge, the figures are original in only the first seven : 

 Wyman, 34 ; Ecker, B ; Gegenbaur (Lankester), A, Fig. 283; Leuret et Gratiolet, A, 

 PI. II ; Laurencet, A, PI. II ; Spurzheitn, A, PI. Ill ; Bourgery and Jacob, A, VIII, PI. 22, 

 Fig. 4 ; Mivart, A, Fig. 74 ; Huxley, A, Fig. 59 ; Cyon, A, Taf. 24 ; McAlpine, A, PI 21 ; 

 Burdon-Sanderson, A, PI. 109 ; Packard, A, Fig. 373. 



Figures of the brain of Menobranchus or other urodelous Amphibia are given in the 

 following ; the accompanying descriptions are usually very meager : Mayer, A ; Laurencet, 



