470 



braue is at this stage sharply defined over the body of the nucleus, 

 but less so on the ramifications. The densely granular nucleoplasm is 

 filled with a large number of rounded, deeply staining bodies which 

 react like chromatin towards all stains and alone are stained by 

 thionin. A delicate linin reticulum connects these bodies with one 

 another. Two dense masses — nucleoli (?) — are rather characteristic 

 of this stage. These stain intensely and from them radiate larger fibres 

 through the nuclear reticulum, often in the form of an aster, but there 

 is no regularity in this character or in their position. 



It is these cells which have been seen by Gonin and Bugnion, 

 at pupation, when they are large and extremely vacuolated. Bugnion, 

 however, doubts the glandular character of these cells, but offers no 

 explanation of their origin, use, or fate. In the embryo and younger 

 larval stages these cells are not found in the same condition in which 

 Gonin found them or as described above, but they exist as different 

 structures as far as appearance and function are concerned. The 

 changes which these cells undergo during larval life are interesting. 

 In a late embryonic stage certain cells of the hypodermis are seen to 

 be enlarging, the nucleus becomes large and round and develops a 

 dense nucleolus. This growth continues until near the time for hatch- 

 ing, when the cell develops a single hollow hair. After hatching 

 and during the early larval stages these short hollow hairs are scattered 

 over the entire surface of the body. They are most numerous in the 

 first larval stage, becoming less and less so until all trace of them is 

 lost in the fourth larval instar. 



The hair is a hollow cuticular tube open at the distal end and 

 continuous with the primary cuticula at the proximal end (Fig. 6, 1). 

 Its interior is filled with protoplasm which is continuous wdtht hat 

 of the cell beneath the hypodermis, connection between the hair 

 and cell being maintained by a delicate canal which pierces the cuti- 

 cula. The cell body is composed of rather dense protoplasm with 

 numerous small, clear vacuoles. The nucleus is large, its diameter 

 being equal to the radius of the cell. The nuclear membrane is well 

 developed and numerous small chromatin bodies are scattered through 

 the nucleoplasm and connected by a linin network. One or two den- 

 sely staining bodies are found in each nucleus and may be the nucleoli 

 or aggregations of chromatin. I have been unable to detect any nerve 

 fibres connected with these cells. 



This condition is found in the middle of one of the early instars, 

 while the animal is actively feeding. When the time draws near for 

 ecdysis, the protoplasmic process is withdrawn from the hair and canal, 

 and the cell itself draws away from the cuticula, leaving a small cavity 



