482 Farmer . — On Spore- Formation and 
vicinity of the nucleolus (Fig. 18). This aggregation is not, 
I believe, to be regarded as an artefact produced merely by 
the inadequate action of fixing-reagents. It is confined to 
these particular divisions in the reproductive cells, and is 
absent from all other dividing nuclei which may have been 
fixed in the same material and at the same time ; thus it is 
not seen in the cells of the vegetative regions of either game- 
tophyte or sporophyte, nor does it occur in the earlier arche- 
sporial divisions. Furthermore it is best seen in those cells 
which in other respects seem to be the best preserved. 
Again, the fact that the aggregated linin was differently 
orientated in even neighbouring nuclei seems to tell against 
the view which would regard it as a mere artefact But 
I would expressly state that I did not observe the nucleolus 
flattened out against the nuclear membrane. This body was 
always free from the wall, though near to it, and thus there 
was no ‘ sichelstadium ’ 1 represented. This in itself is not 
perhaps important, since Zimmermann was unable to recognize 
it in all the spore-mother-cells which he investigated (e. g. 
Hyacinthus caudicans ). Humphrey 2 has suggested that the 
Sichelstadium of Zimmermann and the paranucleolus of Stras- 
burger may be due merely to the faulty penetration of 
reagents, but I do not think that either of these structures 
corresponds with the aggregation of linin I have just de- 
scribed. Moreover an identically similar appearance is seen 
in the homologous mitoses of animal cells, and my friend 
Mr. J. E. S. Moore informs me that it can, in some favourable 
cases, be discerned in the still living cell. At the same time 
it must be stated that at this particular epoch in the life of 
the cell, the protoplasm is very sensitive to the action of 
reagents. It is exceedingly difficult to fix properly, and it 
displays a tendency to break up into lumps on a slight 
provocation. Moreover it has suddenly changed its affinity 
for stains, and now greedily absorbs dyes such as safranin, 
which at other times but slightly affect it. Everything points 
1 Zimmermann, Morphol. u. Physiol, d. Pflanzenzelle, Bd. II. Heft 1, p. 9. 
2 Humphrey, Nucleolen u. Centrosomen, Ber. d. deutsch. Bot. Gesellsch., 1894, 
