PLATE 4 



EXPLANATION OF FIGURES 



19 A, median longitudinal section through the gland shown in figure 18, 

 A, as seen under low magnification. 



20 High magnification of the gland wall in the region inclosed in circle 1, 

 figure 19. 



21 High magnification of the gland wall in the region indicated by circle 2, 

 figure 19. 



22 Transverse section through the deeper part of the duct of the cloacal 

 gland of an 80-cm. caiman. 



23 Transverse section through the same gland as represented in figure 22, 

 but cutting through the middle region of the gland proper, deeper down than 

 the plane of section 22. 



24 Transverse section through the same gland as represented in figures 22 

 and 23. The plane of this section is still farther from the duct and passes through 

 the deeper region of the gland. 



25 High-power sketch of oil droplets extracted with 80 per cent alcohol from 

 the cloacal gland of a 1.6-meter caiman and deposited upon a slide by the evapora- 

 tion of the alcohol. 



26 Low-power sketch of a segment cut from the middle region of the gland 

 shown in figure 18, B. The segment extends from the capsule, cp, to the center 

 of the gland, and is represented chiefly to show the three typical regions whose 

 cell details are shown in the following three figures. 



27 Details, as seen Under moderately high magnification, of cell structure 

 in region 1 of figure 26; this region includes the capsule, cp. 



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