492 MONTGOMERY. [Vol. XV. 



it does not appear to contain vacuoles. The nucleus itself is 

 somewhat elongate and irregular in outline, and, owing to its 

 maximum degree of contraction (a characteristic of the end of 

 the metaphase), its chromatin builds a dense network within it. 

 A study of the cell body at this stage allows us to follow 

 the morphological changes undergone by those nucleoli which 

 had been discharged by the nucleus (Figs. 198-203). The 

 cytoplasm gradually assumes a reticulate or a somewhat granu- 

 lar structure, and finally a most regular vacuolar or alveolar 

 structure. As the cell body decreases in size the discharged 

 nucleoli lying in it gradually stain less deeply, they lose their 

 rod-like form, and no longer remain isolated, but all the nucleo- 

 lar substance in the cytoplasm gradually becomes confluent, 

 and becomes arranged in the form of a coarse, irregular network 

 of substance distributed in the cytoplasm, and readily distin- 

 guishable from the latter by its different staining properties 

 (Figs. 201-203). By a hasty inspection this network of nucle- 

 olar substance might appear to represent branches of the 

 nucleus, but a careful study shows that at this period of its 

 growth the nucleus has no branches. As the cell continues to 

 become smaller the amount of nucleolar substance in the cyto- 

 plasm gradually becomes less and less, first the network at the 

 periphery of the cell disappearing, then that in the vicinity of 

 the nucleus, until at the conclusion of the metaphase no nucle- 

 olar substance is any longer to be seen in the cytoplasm. I am 

 unable to determine whether it is finally discharged through 

 the cell membrane or whether it becomes metamorphosed into 

 cytoplasm ; it certainly is not excreted through the cell duct, 

 since no nuclear substance occurs in the latter, and at this 

 stage the duct is no longer an open tube, but all the secretion 

 corpuscles having been expelled from it, it is again filled with 

 cytoplasm. The suggestion may be made that at least a portion 

 of this nucleolar substance remains in the cytoplasm, so that in 

 the succeeding prophase the nucleolus within the nucleus might 

 find the material necessary for its growth in the nucleolar sub- 

 stance suspended in the cytoplasm ; thus there might be, in the 

 history of the nucleolar substance, periods of its expedition into 

 the cytoplasm alternating with those when it is again taken 



