244 CLAP p. [Vol. XV. 



is easily demonstrated, while the origin of the nerves and their 

 connection with the organs becomes the great problem, as in the 

 case of other teleosts. 



In stages represented in Fig. i8 it is impossible to detect 

 any nerve fibres accompanying the growing line on the side 

 of the body. The whole line has the appearance of being an 

 extension of the mass of ganglion cells. This seems the more 

 striking as the entire string of cells constituting the rudiment 

 of the lateral line in Batrachus seems to occupy the same relative 

 position as the extension oi ganglionic fibres in Acanthias. 



Wilson (14) states that he has been unable to trace the 

 origin of nerves in the Bass. He says in regard to the lateral 

 branch of the vagus, that he could not distinguish it "during 

 embryonic life " nor " in the larvae of two or three days." 



It is difficult to reconcile Hoffmann's (18) observations on 

 Salmo with the facts brought out by Wilson (14) or with the 

 conditions existing in Batrachus. That the origin of the sense 

 organ rudiment precedes the appearance of the nerve in both 

 the Bass and Batrachus can hardly be doubted, while from the 

 description of the "growing sensory tissue" in the skin of 

 Amia, Allis (2) surely conveys the idea of the early appear- 

 ance of the sense organ rudiment. 



3. Formation of canals. — Figs. 7-1 1 represent the appear- 

 ance of the head of Batrachus during the period of the 

 enclosure of the organs in canals. The plates of Allis show in 

 ■detail the different steps of this process of canal formation, 

 and a very full account of the same is to be found in the admi- 

 rable paper on the development of the lateral line organs of 

 Amia. Previous to this paper, we have the accounts of canal 

 formation in Cottus gobio by Bodenstein (9), and in Plateria 

 by Schulze (24) and Solger ^25), but the illustrations of the 

 subject, as well as the accounts, are not so full and clear as in 

 the case of Amia. 



The appearance of the head during these stages is almost 

 identical in Amia and Batrachus. At the time of hatching, 

 the organs are not apparent on the surface, but after treatment 

 with picro-sulphuric acid they may be seen below the surface 

 as whitish spots or irregular lines (Fig. 6). 



