114 NATURE NOTES. 
NOTE ON THE DIVISION OF SuN-ANIMALCULES. 
In January 1898, on examining the contents of a small, 
wide-mouthed glass bottle which had been standing for some 
days in a greenhouse, it was found that, besides some fila- 
ments of JVostoc, and one or two other alge, there was a 
very large number of sun-animalecules. Many of these were 
dividing, and I took the opportunity of watching the process. 
Its early stages appear to take a fairly long time. For 
instance, a beautiful specimen, which, from its size and shape, 
appeared about to divide, was watched for three-quarters of 
an hour, but did not display any noticeable change. Another 
specimen, however, I was fortunate enough to observe at the 
critical moment when the actual separation began, and the 
process, from that moment to its consummation, occupied 
only twenty minutes. 
The ordinary single sun-animalcule is almost perfectly 
circular in outline; and its rays, or delicate pseudopods, 
radiate from one centre only; but a sun-animalcule about 
to divide is of an oblong shape, its breadth being equal to 
that of an ordinary individual, and its length nearly double 
(see fig. 1); and the pseudopods, if studied carefully, will 
be seen to radiate from two centres. 
The actual division, as I saw it, began by the central 
portion of this oblong body becoming slightly narrower than 
the two ends; and this narrowing continued till the whole 
organism looked like a dumb-bell, having a round mass at 
each end, and a somewhat thick band in the middle (see 
fig. 2). Presently, at one end of the band, appeared a slight 
longitudinal flaw, which widened till the band was split, 
from that end to the centre, into two narrow strips (see 
fig. 5). Meantime the two round masses were moving con- 
tinuously further apart, and the band was consequently 
being drawn out thinner and longer; and it was easy to see 
that there were now two sun-animalcules, joined together only 
by a very narrow link, The moment of actual separation 
was difficult to determine, as the band became so fine and 
thin that it seemed to melt rather than break into two. 
After the separation seemed really effected, I followed the 
