History of a transient nervous apparatus in certain Ichthyopsida. 425 



Fig. 103. A similar group with capsule - cells from an embryo 

 (No. 245) of 54 mm. 



Fig. 104. A group of ganglion-cells from an embryo (No. 100) of 

 60 mm. Magnif 500. 



NB. In Figs. 101, 102, 103 and 104 degeneration has hardly set in. 



Fig. 105. A group of ganglion-cells from an embryo (No. 255) 

 of 71 mm. Magnif (Seibekt 4 mm) 225. 



Figs. 106 a, 106 b. Degenerating cells in the posterior fissure of 

 the cord. Embr. No. 261, 8,7 cm. Magnif as before. 



Fig. 107. Two degenerating cells from the same embryo. These 

 two lie in connective tissue just dorsad of the cord. Magnif as before. 



Figs. 108 a and 108 b. Degenerating ganglion-cells in the posterior 

 fissure of an embryo in which the fissure is half completed. Embr. 

 No. 285, 10,5 cm. Magnif as before. 



Figs. 109, 110. Similar cells with degenerated nerve-processes 

 from an embryo (No. 282) of over 10 cm. Magnif as before. 



Fig. 111. From the same embryo. It also shows a degenerating 

 cell in the myotome. Magnif. as before. 



Figs. 112 and 112 a. Degenerating cells from an embryo (No. 263) 

 of 12,25 cm. Permanent central canal approximately complete. Region 

 of the thymus. Magnif. as before. 



Figs. 113 and 113 a. Similar cells from an embryo (No. 294) of 

 14 cm. Magnif as before. 



Plate 29. 



Fig. 114. Ganglion-cells from embryo No. 245 (54 mm). Magnif. 525. 



Fig. 115. Degenerating cells from embryo No. 261 (see Fig. 106). 

 The vacuolation of the lower cell is noteworthy. Magnif, as before. 



Fig. 116. Degenerating cells from embryo No. 263 (12,25 cm). 

 Magnif. as before. 



Fig. 117. Similar cells with degenerated processes from embryo 

 No. 294 (14 cm). Magnif 230. 



Fig. 118. Similar cells from the same embryo. Magnif. 525. 



Fig. 119. Cells from embryo No. 315 (over 16 cm). Magnif as 

 before. 



Figs. 120, 121. From the same embryo, showing also the remains 

 of capsule cells (cc). Region of the thymus. Magnif (Seibert 4 mm) 

 225. 



Figs. 122, 123. Greatly degenerated cells from embryo No. 323 

 (19 cm). Magnif. (Seibert 4 mm) 225. 



Fig. 124. Similar cells from embryo No. 322 (19 cm). Magnif. 

 as before. 



Fig. 125. A much shrunken degenerated cell lying in a cavity and 

 encapsuled in connective tissue near the myotome (m.p) from embryo 

 No. 294 (14 cm). Magnif. as before. 



