-5^ JOUKNAI, OF COMPARATIX E NeUHOLO(;Y. 



drawn. Towards the conclusion of the folding process 

 taking place in the ectoderm, by means of which the massive 

 central organ is formed, but before its separation from the 

 ectoderm, one sees in the fore half of the embryo (head 

 region) three cords, the median neural and the paired lateral 

 cords, which latter, on either side, correspond entirely to the 

 intermediate fascicles (Zwischenstrang) of His (Fig. i z).(') 

 But I have not ascertained the succeeding phase since, as I 

 now see, I have lacked the connecting links. I assumed that 

 in the separation from the ectoderm the paired — /.e. , the 

 intermediate — fascicles came at the same time to lie on both 

 sides of the median neural cord, that is to say, of the massive 

 brain. That is not the case; the paired rudiments move 

 farther mesad together, so that they unite dorsad of the brain 

 cord, into a plate lying between this and the epidermis 

 (Fig. 2 d P), and which is distinguished from the regularly 

 biserially arranged elongated epithelium-like cells of the 

 brain by reason of the irregular and, subsequently, loose dis- 

 position of their elements. This plate exhibits the same 

 structure which His had already sketched, in 1879, in a 

 Scyllium embryo and Beard more recently has drawn in 

 various elasmobranchs and of the chick. 



Not to anticipate the difficult question as to which parts 

 of the peripheral nervous system are derived from this plate, 

 in our terminology I will refer to it neither as ganglion- nor 

 nerve-plate, but call it the dorsal brain-plate., since, although 

 divided into three segments, it extends over the whole length 

 of the brain. Furthermore, in the spinal cord I find the plate 

 not so distinct and represented by a double row of cells, 

 which my pupil. Dr. Victor Rohon, has first described, (■') 

 albeit from later stages, in the trout. 



Next the cells of the dorsal brain-plate advance laterad 



1 Compare my drawings in the Arch. f. Mikr. Anat., 1890, Bd, 35, Taf. XXVIII, Fig. 

 25, and His' figure in the Arch. f. Anat. u. Phys., 1879, Anat. Abt., p. 465. 



2 " On the Histiog. of the Spinal Cord of the Trout," Sitzgsber. d. math, physik. 

 Kl. d. K. Bayer. Acad. d. W., Munchen, 1884, Heft I, p. 39. 



