426 MONTGOMERY. [Vol. XV. 



to be a light yellow. In a preparation stained with haemato.xy- 

 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 AmphiporHs glutinosiis 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. catcmilatmn are more irregular 

 in form and dimensions and stain less intensely than those of 

 the fourth stage oi Ainp/iiporus. 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 : 



