1901 } EREMOSPHAERA AND EXCENTROSPHAERA 319 
is certain that in the forms found growing in this country 
zoospores must be very rarely, if ever, formed. 
The rejuvenescence described by Chodat (1), wherein a cell 
instead of dividing simply slips out from the old sheath, was 
frequently seen and is represented in fig. 5. Whether this can 
really be termed a rejuvenescence, according to the ordinary use 
of the term, is a question. It seems as though this condition 
can hardly be different from those which show a succession of 
walls, except that in the first case the outer wall is not strong 
enough to hold the cell, and it slips out as indicated. There 
never appears to be any change in the contents of the cell, not 
€ven in the arrangement of the chromatophores. 
In the mud at the bottom of the water containing Eremos- 
phaera, there will usually be found a considerable number of 
resting cells. These are of the typical brick-red color, and gen- 
erally show successive layers of sheaths. They contain large 
quantities of oil, and in no way appear to differ from the same 
type of spore in other algae. So far as observed, the develop- 
ment of the resting spore was not accompanied by the formation 
of any new cells. The red color was gradually lost, the chro- 
matophores became more and more prominent, and the normal 
vegetative appearance of Eremosphaera was the result. Usually 
the resulting cell is quite large and division takes place in a very 
short time. No division of the resting spores was observed, the 
condition indicated in fig. 79 being an example of where two 
cells passed into the resting condition almost immediately after 
division, and before they had time to enlarge. This is not an 
infrequent occurrence. 
TAXONOMIC POSITION. 
It is evident from the foregoing that there is no reason for 
supposing that Eremosphaera is related to the desmids or to any 
of the Conjugatae; neither does it seem possible to show that 
it forms any part of the life history of any of the higher crypto- 
gams. The theories of Henfrey (5) and Hofmeister (6) may 
also be dismissed, so that there only remain the two positions 
