EXPLANATION OF THE TLATES. 73 



Fig. 24. Section from the same medulla, still higher up, showing the formation of the auditory and 

 glossopharyngeal nuclei. 



PLATE VII. 



Pigs. 25, 26, 2'7 and 28 are from the human medulla, and show the gradual development of the olivary 

 bodies as seen in transverse sections and their relations to the hypoglossal roots. Fig. 25 is from 

 the same section as Pig. 20 : Fig. 26 is from a section a little higher up than Fig. 21 : Fig. 2*1 is also 

 from a section a little higher than Pig. 22 : Fig. 28 is from the same section as Fig. 23. 



PLATE VIII. 



Fig. 29. Transverse section from the human medulla, showing the central part with the raphb and 

 the olivary commissure, from the upper part of the medulla. 



Pig. 30. Longitudinal section through the human olivary body, showing the convolutions of the 

 lamina or cor2nis dentatum. The section is made obliquely inwards in a direction nearly parallel to 

 the hilus, through the niost dense portions of the lamina. 



Pig. 31. Longitudinal section through the human olivary body, the section being made at right 

 angles to the raphe, showing the outermost portions of the lamina, a, a, the raphe. 



Pig. 32. Longitudinal section through the olivary body in the same direction as the preceding, but 

 further inwards, showing the convolutions of the gray lamina cut through in a somewhat oblique 

 direction, a, a, the raphe. 



PLATE IX. 



Fig. 33. Transverse section of the medulla of the cat, showing the auditory and glossopharyngeal 

 nuclei. 



Fig. 34. Section from the same medulla, a little higher up, showing the very large, posterior audi- 

 tory root and the nucleus. 



Pig. 35. Section from the same medulla, still higher up, showing both divisions of the auditory root, 

 as well as the connection between the nucleus and the cerebellum, with the formation of the upper 

 olivary bodies. 



Pig. 36. Section from the same medulla on a level with the facial roots, showing the roots of the 

 sixth pair, the facial and auditory nerves together with their nuclei. Anteriorly the upper olivary 

 bodies are seen, and the broad wavy bundles constituting the trapezium. 



PLATE X. 



Pig. 37. Group of cells from the anterior portion of the hypoglossal nucleus of the sheep, magnified 

 120 diameters, from a transverse section. A, A, A, bundles connected with the hypoglossal roots : 

 B, B, B, bundles derived from the vagus roots, passing along the outer margin of the nucleus on their 

 way to the raphfe : D, fibres derived from the hypoglossal roots, passing into the deeper portion of the 

 nucleus and curving backwards towards the vagus nucleus. 



Fig. 38. Group of cells from the vagus nucleus, from a transverse section of the medulla of the 

 sheep, magnified 120 diameters. V, bundle of fibres constituting the vagus roots, some of which are 

 seen to turn inwards towards the cells and deeper lying parts of the nucleus, while others sweep around 

 the margin of the hypoglossal nucleus in the direction A, A. 



