Xll LIST OF ILLUSTRATIONS. 



FIG. PAGE 



15. Transverse section through the neural tube, neural crest and 



ectoderm of Amblystoma at a later stage than that shown in 



Fig. 14 3 6 



16. Same as Fig. 15, later stage 37 



17. A part of the spinal cord of an i8-day Catostomus embryo, 



showing the giant ganglion cells 38 



18. Figures of the brain of a selachian embryo (Squalus acanthias) 



to show the history of the neuromeres. After Locy. ... 39 



19. Figures to show the history of the neuromeres in a bony fish 



and in the chick. After Hill 40 



20. The brain of a pig embryo of 12 mm. from the right side. 



From Minot as drawn and revised by Dr. F. T. Lewis. . . 41 



21. Transverse sections through the region of the optic vesicle in 



embryos of: A, Torpedo ocellata; B, Gallus domesticus; 



C, Cavia cobaya. After Froriep 42 



22. The development of the optic vesicles in Amblystoma punc- 



tatum 43 



23. A part of a transverse section of the inferior lobe of the stur- 



geon, stained by the Golgi method 47 



24. A horizontal section of the nucleus praeopticus of the sturgeon, 



by the Golgi method 48 



25. A part of a transverse section of the optic lobe of the sturgeon, 



by the Golgi method 49 



26. The ganglion of the IX nerve in Amblystoma punctatum at 



the time of formation of the central processes 51 



27. A few cells of the trigeminal ganglion of Amblystoma puncta- 



tum with the fibers of the ramus mandibularis growing out 

 from them 51 



28. A, a diagram of the head of Petromyzon at a stage when the 



neural crest is segmented into the anlages of the cranial 

 ganglia. B, a similar diagram at a later stage when all the 

 cranial nerves are to be recognized. After Koltzoff. ... 52 



29. Three diagrams of the head of Squalus acanthias to show the 



differentiation of the neural crest into the cranial ganglia. 

 After Neal 53 



30. A reconstruction of the peripheral nerves in a four weeks 



human embryo, 6.9 mm. long. From Streeter 54 



31. Reconstruction of peripheral nerves in four weeks human 



embryo, 7.0 mm. long. From Streeter 55 



