Kingsbury, Brain of Nectwus. 143 



of the nerve fibers rendered the course, relation and division 

 of the nerves easy to determine. It is not thought, however, 

 that this method would be applicable to larger brains, on 

 account of the expensiveness of the fluid and its low power of 

 penetration and the brittleness of the tissue induced. It was 

 most useful in the study of the oblongata and the origin of 

 the cranial nerves, where the results appeared more satisfactory 

 than those gained by the Weigert method ; the caliber of the 

 fibrers and their relations were shown with the utmost distinct- 

 ness. Tissue cut in collodion by Fish's oil method ('93) could 

 be mounted without further treatment, or a delicate nuclear 

 stain obtained by the use of safranin. Babes' first solution was 

 employed (Formula : concentrated alcoholic solution, 50 c. c, 

 concentrated aqueous solution 50 c. c). The staining required 

 two or three minutes, and 95 per cent, alcohol was used for 

 washing out; (Lee, '93.) The shorter silver nitrate method of 

 Golgi was employed in the study of amyelinic fiber tracts and 

 of cells, though the unavailabity of larval material rendered the 

 results less satisfactory than they otherwise would have been. 

 The usual formulas for the solutions were employed and both 

 double and single impregnations applied. 



ECTAL FEATURES. 



The dorsal aspect of the brain of Necturiis has already been 

 well shown by Osborn and Wilder. Its extreme length is very 

 striking and the impression of a stretching betwen the myel and 

 the olfactory capsules is strong. The pons flexure, which is pres- 

 ent in Triton, and Diemyctyliis and is marked in Desuio- 

 gnathiis is very slight in the adult Nectnriis. The cranium 

 also is not nearly filled by the brain, and the olfactory nerves 

 are long nearly equalling in length the combined prosencephal 

 and rhinencephal. In the larval Nectmus however, the cranium 

 is quite filled by the brain and there is a decided pons flexure, 

 as well as a weaker neck flexure. The adult condition probably 

 indicates that the growth of the brain and skull have proceeded 

 at quite different rates, and that this difference is much greater 



