622 Wolfe, — Cytological Studies on Nemalion. 
region, there is, it would seem, little reason to doubt that a substance 
originally stored in the nucleolus is passing in the manner indicated to 
this position, and further, that this substance is, from its subsequent history, 
certainly to be identified with chromatin. 
These chromatic masses are now directly organized into chromosomes 
without, so far as could be certainly determined, the intervention of a 
spireme stage (Figs. 58-60), and very soon are apparently drawn from 
a general equatorial position to the nuclear plate (Figs. 61-6 5). After splitting 
has occurred, the daughter-chromosomes remain separate for a considerable 
time (Figs. 66 and 69), eventually, however, fusing into two or three masses 
(Figs. 70 and 71), which further fuse into the single centrally placed 
nucleolus (Fig. 72), finally assuming the appearances already described as 
characteristic of the resting nucleus. 
In the development of the gonimoblasts, but not elsewhere, conditions 
were observed which cannot, it would seem, be explained upon any other 
assumption than that a portion of the nucleolar substance is expelled from 
the nucleus in the prophases of division (Figs. 56 and 68). It could not 
be determined whether or not such 'extruded masses represent a substance 
other than chromatin located in the nucleolus, and the homologue of the 
so-called plasmosomes, or true nucleoli. Inasmuch, however, as its reaction 
to stain, as well as its mode of origin, appears to be entirely similar to that 
of the chromatin, the presumption is in favour of identifying it with that 
substance. 
In a recent paper on the nucleolar conditions of Phaseolus (’ 04 ), Wager 
has shown that the nucleolus in this plant is simply a storehouse for the 
greater portion of the chromatin, which, as division approaches, passes out 
of that body into the spireme-thread through fibrous connexions. Although 
in Nemalion no reticulum is present and no spireme is formed, the chro- 
matin, which, as we have seen, is in this instance wholly confined to the 
nucleolus, passes put from it along fibrillae in much the same manner. The 
nucleolus of Spirogyra , according to numerous investigators, is also con- 
cerned to a greater or less extent in the formation of the chromosomes ; 
Moll (’ 93 ), for instance, regarding all the chromatin as derived from that 
body, while Van Wisseling (’ 98 ) finds that only portions of two chromo- 
somes owe their origin to the nucleolus. Golenkin ( J 00 ), in his paper on 
Sphaeroplea , describes conditions according to which the nucleolus breaks 
up directly into morphological chromosomes. This author goes further in 
stating that nuclei organized upon this plan are characteristic of many 
green Algae and Musci. In view of the fact that Golenkin did not section 
his material, it would seem entirely possible that the fibrillae above 
described might easily escape such an examination, and altogether likely 
that a method better adapted to reveal such detail would show conditions 
which would bring these forms more nearly into harmony with the accounts 
