66 WARO NAKAHARA 



nucleic acid according to the higher percentages of phosphorus 

 and the lesser percentages of albumen contained in those com- 

 pounds, and the fact that it is the nucleic acid that determines 

 the staining of the nuclear substance is shown by Lilienfeld, 

 Kossel, and others (Wilson, '00, Mann, '02, Jones, '14). 



In 1893, Zacharias (later, Heidenhain, '94) showed that in 

 staining the preparations of the nucleins containing different 

 amounts of phosphorus, with alcoholic solution of acid-fuchsin 

 and methyl green, the nucleic acid takes a pure green color, 

 but that the nuclein poorer in phosphorus and that poorest in 

 the same element stained bluish violet and pure red respectively. 



Heidenhain ('94) applied this to the case of certain granules 

 in the nucleus of the leucocytes and demonstrated that these 

 granules may show different color reactions by combining with 

 or giving off phosphorus, although they are all exactly aUke in 

 morphological characters. The very interesting case of the 

 changes in color reactions (as well as in sizes) of chromosomes 

 in the eggs of Pristiurus, first described by Riickert ('93) has 

 been beautifully explained by Wilson ('00) in similar manner. 



Applying these principles to the case under discussion, and 

 taking into account the interpretations of somewhat similar 

 changes in chromatic bodies by the previous authors, we may 

 say that the nucleoli originally contain some amount of phos- 

 phorus, but as they migrate into the cell-body, the phosphorus 

 seems to be given off from their composition. The migrated 

 nucleoli may, therefore, be considered as albuminous granules, 

 almost or entirely free from phosphorus. 



Considering the chemical composition of the silk-fiber, we see 

 that this statement on the chemistry of the migrated nucleoli 

 is perfectly acceptable as that of a constituent of the former, 

 provided that there may be some other substance given off, in 

 addition to the nucleoli, for the formation of the silk-fibers. 



IV. CONCLUSIONS 



1. In the silk-gland cells of insects studied, a portion of the 

 nucleoli migrates into the cell-body, and it forms at least a part 

 of the secretion products of the cell. 



