14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



EXPLANATION OF PLATES 



PLATE I 



Fig. I. A low-power drawing of a transverse section through the adrenals and 



adjacent structures of a 40 cm. alligator. 

 Fig. 2. A medium-power view of part of a transverse section of the adrenal of 



a 75 cm. alligator, showing the massing of the chromaphil cells, under the 



capsule. 

 Fig. 3. A part of a transverse section of the adrenal of a 60 cm. alligator as 



seen under a magnification of about 500 diameters. The region here shown 



was about half way between the center and the periphery of the gland. 

 Fig. 4. A figure to show the shape and position of the thyroid gland in a 40 cm. 



alligator. About life size. 

 Fig. 5. A portion of the thyroid and parathyroid glands of the alligator as seen 



under fairly low magnification. 

 Fig. 6. A few alveoli of the thyroid gland of the alligator under a magnification 



of about 400 diameters. In some glands there is more interalveolar con- 

 nective tissue. 

 Fig. 7. A section through the parathyroid shown in figure 5, magnified about 



400 diameters. 



PLATE 2 



Fig. 8. A section of the parathyroid and post-branchial body of a 70 cm. alliga- 

 tor under low magnification. 



Fig. 9. A portion of the section shown in the preceding figure, drawn under 

 much greater magnification. 



Fig. 10. A transverse section of the thymus gland of the alligator as seen under 

 fairly low magnification. 



Fig. II. A small portion of the thymus gland, shown in the preceding figure, 

 magnified about 400 diameters. 



Fig. 12. A low-power sketch of a section through the spleen of the alligator, 

 cut at right angles to the long axis of the organ. 



Fig. 13. The splenic pulp of the alligator magnified about 500 diameters. 



PLATE 3 



Fig. 14. An outline sketch of a ventral view of the brain of the alligator to 



show relative size and position and the hypophysis. 

 Fig. 15. A lateral view of the brain and hypophysis shown in the preceding 



figure. 

 Fig. 16. A low-power, camera sketch of a sagittal section of the infundibulum 



and hypophysis of the alligator. Anterior end to the left. 

 Fig. 17. A low-power, camera drawing of a transverse section through the 



nervous part of the hypophysis of the alligator. 

 Fig. 18. A part of the glandular region of the hypophysis of the alligator, under 



high magnification. 

 Fig. 19. The middle region of the hypophysis of the alligator, under high 



magnification. 

 Fig. 20. The nervous part of the hypophysis of the alligator, under high 



magnification. 



