Explanation of Plates XX, XXI. 



All figures drawn with a camera lucida. 



What we consider the nucléoles have been, except in figure 7, colored carmine, 

 and the chromatin granules blue. 



In figures 1 — 8, except figure 7, no attempt has been made to show contents 

 of nuclei. 



Plate XX. 



Fig. la and b. Two small cells from anterior end of secreting portion, showing 

 simple nuclei, x 240. 



Fig. 2. A larger cell, the more complex nucleus of which shows a radial arrange- 

 ment of branches, x 240. 



Fig. 3, A nucleus which occupies a large proportion of the cell, a = points 

 where branches overlap, x 240. 



Fig. 4. A nucleus occupying a relatively small amount of space within the cell. 

 a = portion which could easily be taken for a separated part, but which 

 is attached to main part by a slender strand, x 240. 



Fig. 5. A nucleus showing how the branches in one part of the cell may be wider 

 than those in another, x 240. 



Fig. 6. A nucleus, a part of which, at first view, appears segmented, the pieces 

 being connected only by slender threads. *'x 240. 



Fig. 7. Enlarged view of the apparently segmented portion of Fig. 6. x 530. 



Plate XXI. 

 In Figs. 9—11, 13, 14, 16, 17, 19, the inner surface, lumen, of the gland is to 

 the right, outer surface marked. Tp. 



Fig. 8. Cell near the anterior end of secreting part of gland, a = point where 

 branches nearly touch. 



Section from a normal gland. Tp. tunica propria, x 1100. 

 Surface view of part of a nucleus from a normal gland, x 880. 

 Section from gland active for five hours, x 1100. 



Surface view of part of a nucleus from a gland after five hours activity. 

 X 880. 



Section from gland after twenty-four hours activity, x 1100. 

 Section from gland of same period of activity, x 725. 

 Surface view of a portion of a nucleus from a gland active for twenty- 

 four hours. X 950. 



27* 



Fig. 



9. 



Fig. 



10, 



Fig. 



11. 



Fig. 



12. 



Fig. 



18. 



Fig. 



14. 



Fig. 



15. 



