xvi LIST OF ILLUSTRATIONS 



PAGE 



FIG. 39. Stages of Disintegration of Frog Embryo Dur- 

 ing Late Cleavage 137 



FIGS. 40-44. Embryonic Segmentation of the Central Nerv- 

 ous System of Vertebrates 139 



FIG. 45. Motor Cell of Ventral Horn of Spinal Cord 



from Human Embryo 158 



FIG. 46. Pyramidal Neuron of Cerebral Cortex of Rabbit 1 58 



FIG. 47. Neuron with Short, Branching Axon, from 



Cerebral Cortex 158 



FIG. 48. Purkinje Cell from Human Cerebellum . . 160 



FIG. 49. Fusiform Cell from Anterior corpus quadrigemi- 



num of Rabbit 160 



FIG. 50. Monopolar Neuron from Mesencephalic Nu- 

 cleus of Fifth Cranial Nerve 160 



FIG. 51. Neuron of Smaller Gustatory Type from Carp 160 



FIG. 52. Neuron from Cephalic Ganglion of Crab, 



Carcinus maenas 162 



FIG. 53. Neuron from Ventral Cord of Earthworm . 162 

 FIG. 54. Development of the Pyramidal Neuron . . 163 



FIG. 55. Purkinje Cell from Cerebellum of New-born 



Infant 163 



FIG. . 56. Two Views, Taken Fifty Minutes Apart, of 

 Same Nerve Fiber, Growing from Group 

 of Embryonic Spinal Cord Cells into the 

 Lymph of Tissue Culture 168 



FIG. 57. Diagram Illustrating Kappers' Conception of 

 the Action of the Bioelectric Current on the 

 Neuroblast 176 



FIGS. 58, 59. Diagrams Illustrating Electrical Polarization 



of a Cell by Bioelectric Currents . . . . 183 



FIGS. 60, 61. Transverse Sections of Spinal Cords, Showing 



Directions of Outgrowths of Early Axons . 186 



FIGS. 62-65. Developmental Stages of Neural Tube and 

 Spinal Ganglia in Salamander, Amblystoma 

 punctatum 197 



