56 • WARO NAKAHARA 



play has remained unsuggested until the appearance of Maziar- 

 ski's ('11) paper, in which he stated that the nucleoli migrate 

 in certain forms into the cell-body, and he regarded these as 

 giving the material for the silk secretion. 



Considering the cytological aspect of the phenomenon of secre- 

 tion in general, the cases in which the secretion granules are de- 

 rived from the nucleoli are very few, if any. Such authors as 

 Garnier COO), for the saUvary gland of the rat, Maximow ('01), 

 for the similar gland of the dog, claim that the migrated ' Nucleo- 

 lekorper' are metabolized into secretion products, but this theory 

 does not seem to be as yet satisfactorily established. The ob- 

 servations on the nucleolar migration by Carlier ('99, '06) in the 

 stomach and liver cells of the newt, by Page and Walker ('08) 

 in the mammalian nerve cells, by Walker and Embleton ('08) 

 in the cells of Hydra, and by Walker and Tozer ('09) in vegetative 

 cells of various plants and animals seem opposed to the view that 

 the nucleolar material can be considered playing a role in the 

 formation of the secretion substance. On the other hand, al- 

 though not completely established, there is a considerable body 

 'of evidence that the chondriosomes, which are widely distrib- 

 uted in the cells of secretory nature, give rise to the secretion 

 granules, as shown by Arnold ('05), Hoven ('10, '11), and 

 Schultze ('11). 



In view of the fact that the nucleoli are now generally consid- 

 'ered as passive by-products of the nuclear activity, and that, 

 so far as the more reliable of previous observations indicate, 

 the active role of the nucleoli in the formation of the secretion 

 products is much to be doubted, it has seemed very advisable 

 to study the phenomenon of the migration of this nuclear 

 element in the silk-gland cells of some insects in greater detail. 



The present paper gives a condensed account of my observa- 

 tions, both morphological and chemical, upon the subject. 

 Before proceeding further, I wish to express my sincere thanks 

 to Professor William A. Riley for his stimulating encourage- 

 ment and valuable advice rendered me during the progress of 

 this work. 



