400 Wm. S. Marshall and C. T. Vorhies, 



anterior portions unite at the base of the labium in a common duct, 

 which leads through the press (fully described by G-ilson [5, 4]) and 

 opens at the tip of the labium. The cells of the conducting portion 

 are numerous in the circumference of the gland, and each possesses a 

 small slightly elongated nucleus; these cells, at the constriction we 

 have mentioned, change abruptly into the larger ones with the bran- 

 ched nuclei which are so characteristic of the spinning glands of Lepid- 

 opterous and Phryganid larvae. 



The cells of the glandular portion are best studied in a surface 

 view by splitting, with a fine scalpel, the gland along one side, then 

 laying it open and flattening it; this is best done after fixation. By 

 this method we were rid of two of the objectionable features which 

 hinder a study of the gland without splitting. The two ditfìculties to 

 be overcome are the curved surface and the secretion, which, filling 

 the lumen of the gland and staining very darkly, obscures the view 

 of the nuclei. The splitting should be done after a short immersion 

 in weak alcohol, when the gland will be flexible and not difficult to 

 handle. Our best results were obtained with Delafleld's haematoxylin, 

 after a long exposure and the removal of the stain from the cyto- 

 plasm with acid alcohol. A counter stain was found undesirable, it 

 obscuring, rather than differentiating, the nuclei, owing to the thickness 

 of the cytoplasm. 



The cells, a single layer of which forms the wall of the gland, 

 are seen to be large (that represented in Fig. 5, one of the largest, 

 measuring 0,47 x 0,3 mm), only two appearing in a transverse section. 

 Meckel [15] claims to have found five forming the circumference of 

 the gland in Collas hrassicae. Each cell is typically the shape of a 

 flattened hexagon, the long axis of which lies in the circumference of 

 the gland. A surface view shows tlie cytoplasm to be of an even, 

 granular structure. 



At the anterior end of the secreting portion the calls are rela- 

 tively very small and the nuclei, correspondingly simple (Fig. 1, a, b), 

 show but a slight indication of branching. As these nuclei do not 

 completely fill the length of the cells, they give, when the gland is so 

 turned as to look down on their ends, an appearance as of two rows 



