256 
Siclnev I. Konihauser 
work is filier aucl the particles more evenly distributed than diuing the 
quiescent periods of the sperniatogonial generations. One deeply stainiiig 
chromatin iiucleolus is present and also a second, less deeply staining, 
body, whicli is often larger than the fü’st, but less distinct in outline. 
FoUoiving tliis stage the chromatin granules gradually assemble along 
definite portions of the network leaving niany of the linin threads devoid 
of clu-oniatin (Plate XIX, Fig. 46). The clironiatic nucleolus is no longer 
visible, but one often finds instead a fine deeply sta inin g thread, ivhich 
probably owes its origüi to this body, although it has been impossible 
to foUow the history of the chroniatic nucleolus continuously. 
The chromatin next fornis definite threads (Plate XIX, Fig. 47), 
which later become more distinct, finer, and less ragged (Plate XIX, Figs. 48, 
49). At no time was a continouous spireni found, but the leptotene 
threads reniaiu connected to one another by fine linin fibers through- 
oiit this Stage. The number of the leptotene thi'eads could not be deter- 
mined with accuracy owing to the tortuous form and scattered arrange- 
ment of the threads. However, in ceUs küled in Hermaxn’s fluid 
(Plate XIX, Fig. 49), in which the threads were loosely scattered and 
distinct, one can be sure that theh number corresponds fairly weU with 
the diploid number of chi-oniosomes^); that the number is greater than 
the reduced number of cliromosonies is certam. 
At the edge of sections stained in crystal violet or Heedexhaix’s 
haeniatoyxhn foUoMiug fixation in Heiolvxx’s fluid, many nuclei of 
the leptotene stage show a single straight non-grauular and deeply stammg 
tliread (Plate XIX, Figs. 47, 48). Several cases were found, such as that 
shown in Figure 48, where one end of this dark thread had united with 
a broader less deeply staining thread. 
Transitions from the leptotene to the zygotene condition coidd be 
foUowed in single cysts, but in no case could a gradual transition in thick- 
ness from the single to the double threads be found. Only occasionally 
did nuclei present a polar arrangement of the leptotene thi'eads (Plate XIX, 
Fig. 50) at a stage when they run side by side beforc their union, such 
as has been described by the Schreixer’s for Myxine, Toinopteris, Spinax 
and Salamandra, by Jaxssens for Älytes, and by Agar for Lepidosüen. 
Leptotene and zygotene threads appear in the same nucleus and often 
two leptetene threads partially united along their lengths were found 
®) In none of the figures have I attempted to draw all the threads in the nuclens, 
for the overlapping threads seen at different focusses would give a far more confused 
appearaaice than that seen in the object itsclf. Üptical sections, or actual sections, of 
teils have been employed for the sake of simplicity whenever recpiired. 
