1 48 Wilson . — On Spore Formation and Nuclear 
p. 144) will equally apply to this stage. In some nuclei exhibiting this 
structure, the cutting off of the above-mentioned body from the nucleolus is 
taking place (Fig. 16), and, if this is to be regarded as a criterion of the 
resting state, the coarser reticulum in these cases must be the result of im- 
perfect fixation. The enlargement of the meshes of the reticulum and the 
increase in the amount of chromatin go on simultaneously ; short thread- 
like filaments of the latter substance are gradually differentiated (Fig. 17), 
until finally a distinct deeply-staining network results (Fig. 18). The latter 
generally extends over the whole nuclear cavity, and consists of a thin 
chromatic thread with regular structure, but interrupted at intervals by 
small irregular masses of chromatic material. Whether at this stage the 
spireme forms one continuous thread, could not be determined on account 
of the numerous intersections which take place. This thin spireme is 
evidently similar to the ‘ filaments minces ’ of Gregoire, and comparison of 
Fig. 18 with Fig. 2 of his work on Lilium Martagoii ( 14 ) shows considerable 
agreement, although, in the case of Mnium , no such distinct areas of 
aggregation (‘ plages ’) of the network are present. 
Contraction now begins in the network as a whole, and finally the 
spireme becomes aggregated to a dense tangled mass which often occupies 
a position towards one side of the nucleus (Fig. 21), but may in some cases 
be centrally disposed (Fig. 19). The exact mode of formation of this first 
contraction figure is somewhat difficult to determine ; it seems that the 
meshes of the network decrease in size, and that during the whole of the 
process the spireme retains its tangled arrangement. Figs. 20 a and 20 b 
were drawn from two successive sections of the same nucleus in which the 
contraction had not proceeded very far, and in these, no parallel arrange- 
ment of the thread, such as described by Gregoire ( 14 ) and by Bergs ( 5 ) 
could be discovered ; where the individual filaments could be distinguished 
they were found to be irregularly entangled. In other nuclei at a similar 
stage, portions of the spireme could be found which had not yet become 
contracted into the general mass (Fig. 19), and a casual investigation might 
lead to the conclusion that in these cases a lateral approximation of separate 
threads was in progress. But careful examination with a high magnification 
proved that these appearances were really due to looping of the thread, 
and not to approximation of distinct filaments. Contraction continues until 
the whole of the thread is collected into a densely tangled mass (Fig. 21), 
generally in close proximity to the nucleolus. At this stage the small 
rounded body derived from the latter during the resting period is still found 
within the nuclear cavity ; its position varies, but it is often found at some 
distance, both from the nucleolus and from the contracted threadwork. 
Numerous preparations were obtained in which the nuclei were in the 
condition of the first synapsis ; but, on the other hand, few were found 
showing the uncontracted network which immediately precedes it, and 
