NOTE ON THE DEVELOPMENT OF AMPHIBIANS. 311 
section of the neural tube of Amblystoma in the anterior 
dorsal region. The band of longitudinal fibres ( L . F.) extends 
nearer to the ventral median than to the dorsal median surface 
of the tube. Goette has described these fibres as originating 
in the external halves of the peripheral cells throughout this 
portion of the tube ; while the internal half of each cell, with 
the nucleus, becomes one of the cells of the grey matter. 
These points I have not been able to follow out with the 
material at my command-. Shortly after the longitudinal fibres 
have appeared another system of fibres arises — the transverse 
fibres or ventral commissure (T. F.). These fibres appear as 
polar outgrowths of the cells which lie internal to the longi- 
tudinal band. They pass ventrally along the inner surface of 
the longitudinal band, and cross transversely the ventral sur- 
face of the neural tube immediately inside the cuticula. Both 
of these systems of nerve-fibres develope later in the posterior 
than in the anterior part of the central nervous system. The 
transverse fibres extend as a continuous ventral commissure as 
far forward as the point where the floor of the mid-brain bends 
ventralwards into the posterior wall of the infundibulum. 
This is shown in median vertical section in fig. 24 g. The 
lateral bands of longitudinal fibres extend forward through the 
hind- and mid-brain, showing the same relations as in the 
dorsal region (fig. 34). On passing from the mid-brain to the 
fore-brain the lateral bands follow the curve of the cranial 
flexure ; and on reaching the morphologically anterior surface 
of the brain, they cross it, blending with each other immedi- 
ately ventral to the optic stalks. The lateral bands thus blend 
into an anterior band, which is cut transversely into the median 
vertical sections, 17 g and 18, at Ch. This anterior band com- 
prises a bundle of fibres, which I would roughly estimate to be 
about twenty times as large as the bundle of fibres which 
appears shortly afterwards on each optic stalk. The course of 
the lateral band (L. F.) in the mid- and fore-brain is shown in 
the lateral vertical section fig. 32 g; the dotted line indi- 
cates the lower median contour of the brain. Fig. 33 shows 
the anterior band (A. F.) of the Frog just behind the optic 
