HARGITT: PENNARIA TIARELLA AND TUBULARIA CROCEA. 185 
43, the nucleus of a half grown egg, and Figure 44, from the nearly 
mature egg shown in Figure 56, present about the same conditions. 
The stains here used, hematoxylin and eosin, gave the small dense 
fragments in the reticulum a purplish red, and the larger vacuolated 
portion a bright red appearance. Figures 45, 46 (Plate 6) are from full- 
grown eggs which had almost entirely withdrawn their pseudopodia; 
a final fragmentation of the nucleoli is taking place. In one case 
there is a chain of vacuolated fragments, in the other the fragments 
are more scattered. Figure 47 is from a nearly full-grown egg, the 
pseudopodia of which were still extended. All the nucleolar fragments 
present in the entire nucleus are shown in the drawing, those lying on 
either side of the section outlined having been drawn as though pro- 
jected on the plane of that section. This shows the largest number 
of fragments that I have ever found. ‘lhe fragments resulting from 
the breaking down of the nucleolus appear to become incorporated 
into the nuclear reticulum, though there are probably some portions 
which are dissolved in the nuclear sap. When the egg has withdrawn 
its pseudopodia and assumed a rounded form, the germinative vesicle 
shows no sign of a nucleolus or nucleolar fragments, and since the 
nuclear membrane has not yet been ruptured, the entire substance of 
the nucleolus has become disseminated throughout the nucleus. 
The nucleolus, and hence the material derived from it, I believe to 
be non-chromatic, since its staining reaction is different from that of 
chromatin. The nucleolar substance, however, becomes incorporated 
into the nuclear reticulum, and perhaps is converted into chromatin. 
Evidence is not lacking to support this contention. For, with hema- 
toxylin-eosin staining the nucleolus at no stage shows any sign of a 
blue color; with picro-hematoxylin it is always yellowish, never blue; 
in the Ehrlich-Biondi acid fuchsin-methyl green combination it is pink 
and not green, though it is sometimes of a darker pink, and in oégonia 
is bluish. Further, the fragments of the nucleolus in the nuclear 
reticulum become changed so as to stain more like the reticulum and 
less like the nucleolus; in the hematoxylin-eosin stain the nucleolus 
is red, the fragments in the reticulum purplish; in fuchsin-methy] 
green the large nucleolus is red, but the smaller fragments in the 
reticulum vary in color, some being red, others blue and still others 
green. ‘l'his seems to me to indicate a rather gradual chemical change 
in the substance of the fragments. In picro-hematoxylin preparations 
the larger pieces are yellow, the smaller ones blue. 
To sum up: the nucleolus during the growth period of the egg seems 
to be composed of non-chromatic substance. It disappears in the 
