426 
MONTGOMERY. 
[Vol. XV. 
to be a light yellow. In a preparation stained with haematoxy- 
lin and eosin, though not very thoroughly colored with the 
latter stain, the large nucleoli of the first nucleolar stage were 
of a light-yellow color, apparently stained only slightly with the 
eosin; those of the end of the second stage were mostly stained 
red, and those of the third stage were stained red, except those 
which had broken into granules, these latter being stained very 
little. In another preparation, in which the eosin had acted 
for one or two minutes longer than in the preceding prepara¬ 
tion, the nucleoli in the first stage were stained orange, those of 
the second stage red, and those of the third stage very slightly 
or not at all stained. Accordingly, they stain more lightly at the 
commencement of the first and at the end of the third stage than 
during the second stage; these differences of stain are probably 
due to chemical differences in the nucleoli at different stages. 
The chief differences between the nucleoli of this species and 
those of Amphiporus glutinosus are as follows : in the former 
there is no stage which exactly corresponds to the first stage of 
the latter, where we found a number of small peripheral nucle¬ 
oli ; in T. catenulatum there are at first one or two large 
nucleoli which are not always peripheral in position. The 
nucleoli in the third stage of T. catenulatum are more irregular 
in form and dimensions and stain less intensely than those of 
the fourth stage of Amphiporus. But the most important differ¬ 
ence between the two species is to be found in the fact that 
in T. catenulatum new nucleoli continue to be produced even in 
the third stage. Thus there are at the periphery of the nucleus, 
between the larger degenerating nucleoli which had their origin 
during the first stage, also much smaller, newly formed nucleoli 
arising while the former are disappearing. Such younger 
nucleoli may be seen at the close of the third stage, when the 
nuclei are largest and chromatin filaments appear in them, 
arranged in contact with the chromatin threads or near to 
them (Figs. 127, 137, 138). These smallest nucleoli of the third 
stage always stain intensely red with eosin, while the much 
larger ones of the first and second stages stain more of an orange 
color with this stain. This difference of staining in these two 
kinds of nucleoli might be explained thus : 
