SECRETORY PHENOMENA IN SILK GLAND. 415 



surrounding the silk core. These bodies were so indistinct that 

 they may have been the result of poor technique. 



Yamanouchi ('22) finds evidence that sericin, or the outer 

 layer of the silk core, is secreted in the posterior portion of the 

 middle region. Blanc ('89) considers that mucous is secreted in 

 the anterior portion of the reservoir in the form of numerous 

 granules, but this point has received little support in subsequent 

 literature. 



(c) Mitochondria. Throughout the whole of the literature 

 dealing with the silk glands of various lepidopteran larvae, no 

 reference has been found which even suggests that the workers 

 suspected the presence of mitochondria in the cells. This may 

 be due to the fact that no investigator has employed specific 

 mitochondrial fixatives. 



Maziarski ('i i) describes certain bodies that are found occasion- 

 ally in the protoplasm as having the form of short "batonnets," 

 and staining deeply. These have a parallel arrangement along 

 the shorter axis of the cell and unite with one another by fine 

 protoplasmic fibrils. The substance of these batonnets is re- 

 fractile and stains with acid stains. Gilson noticed these bodies 

 and thought they were related to functional processes of the 

 protoplasm in that they have the appearance of little tubules 

 filled with secretory substance. Maziarski did not find these 

 bodies consistently present in all of his material. 



After fixation with Regaud, and staining with Altmann's 

 anilin acid fuchsin, methyl green, clear-cut evidence of the 

 existence of mitochondria in the cells of //. cunea has been 

 obtained. 



i. Posterior Region. The mitochondria in the posterior region 

 are very numerous, especially between portions of a nucleus and 

 toward the lumen. In whatever part of the cell the mitochondria 

 may appear, they always show a characteristic orientation with 

 their longitudinal axis toward the lumen. There is no evidence 

 that these bodies have any direct relation to the nucleus for 

 they do not radiate from it or tend to cluster around it (Figs. 



1,2). 



Their usual shape is filamentous, rod-shaped or granular. 

 Where active secretion is taking place, long filaments are present, 



