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



extended from the outer membrane as far as, or slightly beyond, 

 the nucleus. 



In the nucleus no noticeable change has taken place, although we 

 found that in its more elongated portions the nucléoles show, both in 

 frequency and extent, a tendency to become elongated. The margins 

 of the nucléoles are still fairly regular, showing as yet but slight, if 

 any, changes from those in the normal gland. 



24 hours (Figs. 13, 14 and 15). The first of the glands, active for 

 this length of time, which we examined, showed such a decided change 

 from those we have so far described that we made a number of other 

 preparations, in fact, more than for any other period of activity. An 

 examination of all these sections shows quite a variation in struc- 

 ture, there being in all of them a much greater change from the 

 normal than in either the two and one-half or five hour periods. We 

 have already explained that in these twenty-four hour periods, the 

 larvae were timed from the removal of the case, and that the con- 

 struction of a new one was not begun at once, but after two, three, 

 or more hours had elapsed. There must also be a great amount of 

 variation in the time of activity, some larvae undoubtedly spending 

 much more time in actual work and consequently using more secretion 

 than others. In a previous work (1. c. page 2) we showed tliat there 

 was a great difference in the amount of repair or of rebuilding done 

 by different larvae in equal lengths of time 



The cytoplasm in the outer half of the cells (Figs. 13 and 14) shows 

 a marked difference from that in the inner half, where it is still simi- 

 lar to what we found it to be throughout the entire normal cell. At 

 that region in the cells where the cytoplasm of the inner and of the 

 outer parts join, quite an abrupt change is noted; this transitional 

 border does not always lie in the central portion of the cell, the rela- 

 tive thickness of the two regions changing in different parts of the 

 gland. In the outer portion of the cells the cytoplasm, instead of 

 having an even appearance throughout, shows very plainly a differen- 

 tiation into two parts which are unlike in appearance. The one is 

 lighter colored than the other and is also of a looser structure; in 

 many specimens vacuoles are present, which in some sections appear 



