422 JOHN BEARD, 



Fig. 57. From a section of the tail-end of an embryo (No. 299) 

 of 15,5 cm. To show a large ganglion-cell extending across the posterior 

 fissure of the cord. Magnif. 225 X I- 



Plate 25. 



Fig. 58. A drawing under low power (50 X 1) t.o localise the 

 structures shown in Figs. 59, 60 and 61. 



Figs. 59, 60 and 61. Fig. 59 shows a degenerating ganglion-cell 

 lying in the myotome of Fig. 58 (gl. c. 2). Fig. 60 is a drawing of a 

 curious group of degenerating cells (? ganglionic) lying near the lateral 

 nerve in Fig. 58. Fig. 61 depicts a normal ganglion-cell occurring in 

 the course of the apparent right sub-epiblastic nerve of Fig. 58. Embr. 

 No. 229, 43 mm. Magnif 500 X I- 



Fig. 62. A diagrammatic combination of several sections, to show 

 two sub-epiblastic nerves and their relations to certain ganglion-cells. 

 Embr. No. 229. 



Fig. 63. A sub-epiblastic nerve with applied ganglion-cells from 

 the same embryo. Magnif. 225 X f- 



Fig. 64. Two ganglion-cells lying in the muscle-substance of the 

 myotome of the same embryo. Magnif. 525 X f- 



Fig. 65. A schematic combination of several sections of which 

 Fig. 64 was one. 



Fig. 66. A transient nerve, with applied nuclei, piercing the myo- 

 tome. Embr. as before, magnif. as in Fig. 64. 



Fig. 67. A combination drawing of several sections, Fig. 64 forming 

 one, to show the sub-epiblastic nerve passing through the myotome. 

 Magnif. 225 X I- 



Fig. 68. Two degenerating ganglion-cells l3àng in the connective 

 tissue of the mesoderm a little dorsad of the spinal cord. Embr. 

 No. 323, 19 cm. Magnif. (?) 500 X I- 



Fig. 69. A curious (V degenerating) cell lying in the ventral region 

 of the cord. It is filled with ])articles (V yolk or fat) blackened with 

 osmic acid. Embr. No. 453, 22 mm. Magnif 225 X I- 



Fig. 70. A similar cell from the forebrain of embr. No. 402, 

 11 mm. Magnif. 500. 



Fig. 71. Portion of a section of the spinal cord of an embrj^o 

 (No. 285) of 10,5 cm, to illustrate the mode of formation of the per- 

 manent central canal. 



Fig. 72. To show the extension of two sub-epiblastic nerves in a 

 combination of several sections from an embryo (No. 419, lO.y mm) 

 treated with chrome-osmic-acetic acid. Magnif. 225 X I- 



Fig. 73. Part of a horizontal section passing through the most 

 dorsal region of the cord. To show the distribution of the transient 

 ganglion-cells in a portion of the trunk. The region of four myotomes 

 is given. Embr. No. 202, 25 mm. Magnif 230 X I- 



Fig. 74. A bipolar ganglion-cell with a "nerve-cell" nucleus em- 

 bedded in the course of one of its processes. Embr. No. 209, 34 mm. 

 Magnif (Leitz 2 mm pantachromatic) 50O X |- 



