SECRETORY PHENOMENA IN SILK GLAND. 4! I 



plasm. Critical observation with high magnification definitely 

 showed nuclear bodies partly within the nucleus and partly in 

 the cytoplasm (Fig. 4). The passage of nuclear bodies into the 

 cytoplasm is a fact that has been described with great care by 

 Maziarski ('11), Nakahara ('17), and earlier workers, as of 

 regular occurrence in the spinning-gland cell; by Saguchi ('20) 

 as occurring in nuclear function of the pancreas cell; and by 

 Ludford ('25) in tissue cultures of fibroblasts of the rats' kidney. 



The staining reaction of these nuclear bodies is of interest 

 because of the fact that although it is more or less variable, yet it 

 tends to show greater affinity for acid stains. (See Chart.) 

 It has been upon reactions to stains that all the conclusions in 

 regard to the relation between nucleus and secretion have been 

 made, since it has been regularly found that the nuclear bodies 

 (nucleoli) and apparently related bodies in the cytoplasm exhibit 

 the same staining reactions. 



The third class of nuclear bodies found in //. cunea has not 

 been described in the literature so far as it has been possible to 

 determine. Because of the similarity between these bodies and 

 the true nucleoli, they will be referred to throughout this paper 

 as "nucleoloid bodies." Meves ('97) mentions the fact that 

 nucleoli may contain several small vacuoles, but in the figures 

 of nucleoli in which he shows this structure, they are no larger 

 than numerous other bodies in the nucleus. Korschelt ('97) in 

 replying to the criticism of Meves, attempts to explain the 

 presence of vacuoles by the hypothesis that the nucleoli or micro- 

 somes are derived from the chromatic substance by some trans- 

 formation evidenced, no doubt, by these vacuoles. Marshall 

 and Yorhies ('06) definitely state that no plasmosome or special 

 structure is formed in the nucleus during secretion in spinning- 

 gland cells of Platyphylax, but mention the fact that sometimes 

 the nucleoli may contain vacuoles but no further significance is 

 attached to the observation; nor did Nakahara ('17) consider 

 as important the presence of vacuoles in nucleoli. In the 

 nuclei of H. cunea, vacuolated bodies are found to be sufficiently 

 definite to attract especial attention. After carefully measuring 

 a large number of such bodies in all parts of the silk gland, it 

 was found that the average diameter is about 4 micra regardless 



