BIGELOW : NUCLEAR CYCLE OF GONIONEMUS MURBACHII. 347 



lum, but with the growth of the nucleus they increase rapidly in bulk 

 (compare Figs. 131, 132, with Figs. 133, 134). From their evidently 

 compound nature (Fig. 133) it may be inferred that their growth is 

 the result of an addition of granules or masses of similar composition to 

 the original mass. Their more or less central position shows that they 

 are intra-nuclear formations, and not, as Montgomery ('98 1 ') suggests con- 

 cerning nucleoli in general, of extra-nuclear origin; while all the evi- 

 dence seems to indicate that they arise in very intimate connection 

 with the nuclear reticulum. Following E. B. Wilson (: 00), we may 

 term them the " accessory nucleoli." 



Shortly after the appearance of these " accessory nucleoli," the reticu- 

 lum of the nucleus, which now measures about 14 p in diameter, com- 

 mences to regain its affinity for stains, and the chromatin commences to 

 reassert itself. This shows itself in the appearance of a very large num- 

 ber of block-like, rather indefinitely outlined aggregations of deeply 

 staining granules scattered throughout the nucleus (Fig. 131), which show 

 an increasing affinity for the iron haematoxylin stain. There is no evi- 

 dence that these receive any accession to their mass from either the chief 

 or the accessory nucleolus, since neither of these two structures exhibits 

 any change in structure or corresponding decrease in volume ; we must 

 therefore suppose that they are formed by a segregation of the chroma- 

 tin granules formerly more generally diffused throughout the nuclear 

 substance, and that their reappearance is due, not to the fact that they 

 were previously masked by any other structures, but in part to their con- 

 densation and in part to changes in their chemical composition resulting 

 in a stronger affinity for stains. These granular masses finally become 

 very numerous, upwards of a hundred being often visible in a single nu- 

 cleus ; and they gradually arrange themselves in rows or strands (the com- 

 mencement of this change is seen in the section represented in Figure 

 132), a process which continues until a variable number of independent 

 strands result ; these now stain strongly, especially in preparations 

 previously treated with chlorine or hydrogen pei-oxide, and frequently 

 exhibit Y- or V-shaped forms, as is seen in the nucleus of which a 

 section is shown in Figure 133. The possibility that such figures may 

 represent either a longitudinal splitting of the strands, or, on the other 

 hand, their synapsis in pairs, will at once occur to the reader ; but which, 

 if either, of these explanations is correct can be settled only by tracing 

 the formation of the individual chromosomes from the strands, and fur- 

 ther discussion of this question is therefore idle until the late prophase 

 of the first maturation divisiou can be studied. The relation of the 



