62 C. T. VORHIES. 



Explanation of Plate I. 



All nuclei figured which are longer in one dimension than in the other lie with the 

 long axis transverse to the long axis of the gland. 



Fig. I. Nucleus of a spinning-gland cell from a larva just hatched ; the single 

 nucleolus is typical in size, shape and position. X i>300- 



Fig. 2. A nucleus from the same gland as that in Fig. i. Nucleolus elongated. 



X 1.300. 



Fig. 3. Nucleus from a larva "just hatched " but probably a little older than the 

 one from which Figs, i and 2 are taken. X 1,300. 



Fig. 4. Nucleus from the same larva as Fig. 3. Nucleole fragmenting. X 1.300. 



Fig. 5. Slightly elongated nucleus from same larva as Figs. 3 and 4. Two nucle- 

 oles. X 1.300. 



Fig. 6. Slightly elongated nucleus from the same larva as Figs. 3, 4 and 5. Two 

 irregular nucleoles. X 1, 300. 



Fig. 7. Elongated nucleus from a larva twenty-four hours old. Nucleoles irreg- 

 ular, three in number. X 1, 300. 



Figs. 8 and 9. Larger nuclei from a larva about one week old, showing further 

 fragmentation of the nucleolus. X 1,300. 



Fig. 10. Nucleus from a larva about one week old, which has probably molted. 

 Twelve nucleoles present. X i,300. 



J"ig. II. Nucleus from a larva about 3 mm. in length. It is probably about two 

 weeks old and has certainly molted. Twenty-two nucleoles. X 800. 



Fig. 12. Nucleus from another larva 3 mm. in length. Many nucleoles. Ends 

 of the nucleus branching. X 800. 



Fig. 13. Nucleus from a larva 5 mm. in length. Branching more complex, and 

 nucleoles more numerous. X ^oo. 



Fig. 14. Nucleus from an adult larva, about 16 mm. in length, containing a very 

 large number of nucleoles. No attempt has been made to represent the chromatin in 

 this figure, as the magnification is not great enough. X I75- 



