374 S. SAGUCHI 



tive material, but a decomposition product which separates in 

 or upon the chromatic elements during the vegetative activity 

 of the cell and nucleus, and which, at the beginning of mitosis, 

 is removed from the nucleus. This conception is termed the 

 'nuclear secretion theory.' 



From my observations referred to above, we cannot arrive at 

 any satisfactory solution of the problem of the origin of the 

 nucleolar substance. In a previous investigation ('15) I have 

 observed that, in the physiological degeneration of certain glan- 

 dular cells in the amphibian epidermis, the nucleus is characterized 

 by the increase of the nucleolar substance, accompanied by the 

 simultaneous decrease of the nuclear substance. From this I 

 have been led to the assumption that the former might be formed 

 at the expense of the latter : a view which was also held, as early 

 as 1888, by Hermann. Since it is obvious from my observations 

 that the nucleolar substance passes out of the nucleus in order 

 to form an essential constituent of the cytoplasm, it must be 

 regenerated either at the expense of the nutritive material taken 

 in from the cytoplasm or by the decomposition of the chromatin 

 substance. I find it possible rather to accept as adequate the 

 explanation that the nucleolus is formed by the participation of 

 the chromatin substance than to regard it as a mere accumulation 

 of nutritive material. This conception is strictly opposed to 

 that of Flemming, Korschelt, and others, and is rather in favor 

 of the view of the 'nuclear secretion theory' of Haecker. I re- 

 gard, however, the nucleolar substance not as worthless decom- 

 position product, but as material necessary to give rise to such 

 an essential substance for the cell activity as mitochondria. 

 The transformation of the nucleolar substance into mitochondria 

 must be thought of as taking place in the following manner: 

 the main-mass of the nucleolus undergoes change in staining 

 reaction at the periphery and gradually is converted into a sub- 

 stance that forms the cortex of the nucleolus. The latter, on 

 the other hand, continually emits small granules or rods, which 

 pass toward the periphery along the nuclear network. These 

 separated corpuscles are those which we have termed 'nucleolar 

 corpuscles.' They, then, pass through the nuclear membrane 



