482 THE AMERICAN NATURALIST. [Vor. XXXIX. 
of time and may occupy even weeks or months. During this 
interval the spore mother-cells increase to many times the size 
of the archesporial cells from which they were derived. There 
is an immense accumulation of protoplasmic material and a cor- 
responding increase in the size of the nucleus and its chromatin 
content. The growth may be continued in the spores after the 
mitoses of sporogenesis, as is characteristically illustrated in the 
great increase in the size of the megaspores in the pteridophytes 
and certain embryo-sacs. The most striking nuclear activity of 
the growth period preceding the mitoses is synapsis. This term 
is applied to a very characteristic gathering of the chromatin and 
linin material in a compact tangle or ball at one side of the 
nucleus and usually near the nucleolus. Nuclei are sometimes 
in a state of synapsis for several days or perhaps weeks as is 
shown by the frequency of the stage in sporogenesis. Thus 
during the entire period of sporogenesis in Anthoceros from the 
inception of the spore mother-cell to the final differentiation of 
the spores (which must take many days) the period of synapsis 
occupies from one eighth to one sixth of the entire time (Davis, 
'99, p. 104). Synapsis has proved to bea very difficult subject 
for study and few investigators have made detailed observations 
upon its events. Some have claimed that synapsis is an artifact 
due either to poor fixation or to a particularly sensitive condi- 
ton of the cell nucleus by which the chromatin was especially 
susceptible to shrinkage but it seems certain now that the 
phenomenon is entirely normal. Miss Sargant (97, p. 195) has 
observed synapsis in the living pollen mother-cell of Lilium 
martagon. Anthoceros presents a particularly favorable subject 
for the study of the effects of fixing fluids on spore mother-cells 
because one may present all sta 
: : ges in the same sporophyte to 
identical conditions. 
which are cccasionally found in cells. Thus Miyake (Annals of 
1903) noted the resemblance to synapsis 
