420 Wra. s. Marshall and C. T. Vorhies, Cytological studies on the spinning etc. 



Fig. 16. Section from a gland which had been active for seventy-two hours. 



X 1100. 

 Fig. 17. Section from gland of one hundred and twenty hours of activity, x 880. 

 Fig. 18. Part of a nucleus from a surface view, showing same period of activity 



as Fig. 17. X 710. 

 Fig. 19. Section of gland after two hundred and forty hours of activity, x 1100. 

 Fig. 20. Section of nucleus from gland of same period of activity, x 1200. 

 Fig. 21. Nucléoles from glands which had been active for same period of activity. 



All X 1100. 

 Fig. 22. Section of a gland taken from a young pupa to show the changes which 



have taken place in its contents, x 880. 

 Fig. 23. Longitudinal section of the mass of secretion. This shows the arrange- 

 ment of the vacuoles in the secretion, which is so common in normal 



glands or those of the shorter periods of activity. 

 Fig. 24. Section showing inner margin of normal gland and adjacent secretion. 



c = cytoplasm of that part of the cell which is just inside of the inner 



membrane, i. Lb = light brown layer which is seen in most sections; 



it lies between the gland and the secretion, s = outer margin of mass 



of secretion. The lettering in the following figures is the same, x 1100. 

 Fig. 25. Similar section from gland after two and one-half hours of activity. 



X 1100. 

 Fig. 26. Inner' margin of cell, showing the processes which are sometimes observed 



at this stage; active five hours. Each process contains numerous darkly 



stained globules and the same, although somewhat smaller, are seen in 



the neighbouring cytoplasm, x 1100. 

 Fig. 27. Section from the same region as Fig. 24, but from a gland which has 



been active for twenty-four hours, x 1100 

 Fig. 28. Similar section from a gland of one hundred and twenty hours activity. 



x 1100. 



