412 Wm. s. Marshall and C. T. Vorhies, 



ilar throughout, although there still remains a marked difference be- 

 tween the inner and the outer halves. The former is noticeably dist- 

 urbed by the entrance into it of the striae which before have been 

 restricted to the outer portions of the cells. This invasion of the 

 inner part by the striae was suggested in glands of one hundred and 

 twenty hours of activity. The outer portion of each cell shows a 

 marked striation, the presence of somewhat elongated vacuoles, and 

 the areas of darkened cytoplasm; these are here mostly in close 

 proximity to the outer boundary of the nucleus, but exceptionally pre- 

 sent along its inner border. In Fig. 20 a view with a higher magni- 

 fication is shown. Along the outer margin of this nucleus the darkened 

 areas are distinctly seen extending in pointed processes toward the 

 outer surface of the gland. 



The nucléoles show a further change in the very great irregular- 

 ities of their contour. Very few are now noticed which show the same 

 even surface characteristic of them in the normal gland, tlie majority 

 presenting an extremely irregular outline, which, in the surface view 

 of the nucleus, becomes very pronounced. The best idea of the various 

 shapes these nucléoles now assume can be obtained from the view 

 (Fig. 21) we have represented. The chromatin granules appear as 

 heretofore, nothing like a grouping of them in any part of the nucleus 

 being noticed. Many of them show a linear arrangement (Fig. 20). 

 The nuclear membrane has, as usual, an even contour along the 

 inner border; on the outer margin, however, it has become very 

 irregular, presenting many pointed processes which project into the 

 adjacent cytoplasm. The two views we have given (Figs. 19 and 20) 

 are not exceptional, this condition being found in any section. As in 

 the last period described, there is here also quite a difference between 

 the distinctness of the nuclear membrane on the inner and outer sur- 

 faces. The latter surface is often almost impossible to distinguish, 

 the contents of the nucleus and the adjacent cytoplasm merging into 

 one another; it is often difficult to say just at what point the bound- 

 ary occurs. 



We wish to record that after pupation, at which time the spinning 

 glands disappear, sections show that the first changes to take place 



