in Plant Cytology. 191 



chromatin alike build up each chromosome, since both share 

 equally in the division process, since both exist in spore and 

 sex cells, and since both, according to my own studies, as well 

 as those of Wisselingh and others, make up the stainable 

 nucleolar substance, may we not regard the general cytoplasm 

 and nucleoplasm as tlie vegetative substance of the cell, the 

 chromatin granules as the highly specialized hereditary substance, 

 and the linin as an intermediate substance which transmits 

 hereditary peculiarities in slow degree from the cytoplasm to 

 the chromatin, and is itself the bearer in part, of hereditary 

 peculiarities. To this we can conveniently return after con- 

 sideration of the nucleolus. 



The literature bearing on the nucleolus has been so recently 

 collected, and expanded from the zoological standpoint in 

 Montgomery's valuable paper, that it may seem necessary 

 only to compare the views there presented. But so rapid 

 have been the advances on the botanical side during the past 

 two )-ears that the views of Wager, Debski, Farmer and 

 Williams, Sargant, Wisselingh and others, might importantly 

 modify our conceptions. 



The resting nucleolus, when fixed and stained, shows a 

 density of stainability that is only and exactly paralleled by 

 the chromatin granules, and to a less extent by the linin. 

 Moreover, the total amount of the latter substances in the 

 perinucleolar area of most embiyonic cells in the resting state, 

 would not account for the bulk of the chromosome granules. 

 On the other hand the vegetative cells of most coniferous 

 plants, and in such growing apices as Passiflora, Nerhan, 

 Bougainvillea, the nucleolus, though distinct, is relatively 

 small, while the perinucleolar area is rich in refractive stain- 

 able substance in the form of loops. As is now gen- 

 erally acknowledged, the resting and dividing nucleolus of 

 species of Spirogyra bears nearly all the chromatin as well 

 as linin material, and in the dividing stage becomes halved, 



