18 SCHULTZE, ON DIATOMACES. 
to the one or the other way. The shape and direction of the 
thread are subject to continual change. The forked division, 
for instance, proceeds from the base of the threads at the 
cell-nucleus to the other ends, which meet together on the 
internal surface of the cell-wall. Or it forms out of the 
forked division a bridge to a thread lying close beside it, 
while the branch part melts away with this. The bridge then 
runs upwards or downwards between both threads; it shortens 
itself, while the latter draw near one another ; finally they 
melt away completely with each other into one, so that now 
a broader stream flows where there were formerly individual 
fine threads. On the internal surface of the cell-wall is 
found a thin, coherent, protoplasmic layer. So it appears 
after the application of reagents, which cause it (the primor- 
dial utricle) to become shrivelled. By means of syrup I 
could bring out here what A. Braun arrived at in the Cha- 
race (‘ Monatsberichte der Berliner Akademie d. Wiss.,’ 
1852, p. 225). The cell-contents, sharply circumscribed, 
drew themselves back from the membrane of the cell; besides, 
the appearance of currents in the interior still continued for 
along time. In this way one can convince himself that the 
granular currents and fluctuations (for such are here fre- 
quently alone present in places), occurrmg in the mid-layer 
of the protoplasm, are not related to the last layer (Haut- 
schicht, Pringsheim) but only to the inner stratum of the 
parietal layer (granular layer). In this way those in Nocéi- 
luca are comparable with the above. In distilled water I 
have seen the appearance of a stream maintain itself in indi- 
vidual cells for twelve hours, and in thin syrup for twenty- 
four. It would be well worth the trouble to try the influence 
of a series of solutions on the movements described, perhaps 
like those made by Kolliker with the spermatozoa. In this 
way interesting disclosures might be expected. 
The movements remarked in the protoplasm of plant-cells 
ought not, in my opinion, to remain neglected, as they may 
act as an explanation of the mysterious appearances of life in 
the sarcode threads of the Rhizopoda, and I recommend the 
comparative study of the former to those who consider the 
threads in Polythalamia as possibly or probably a compound 
of small cells. In Tradescantia the same phenomena occur 
in undoubted cell-contents, which must, therefore, be related 
to animal life. 
Of Rhizosoleniz I have observed two different species. 
The largest, and by far the most abundant, is undoubtedly 
identical with Brightwell’s R. styliformis, described in the 
‘Quarterly Journal of Microscopical Science,’ Jan., 1858, 
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