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the year it was of little use to search for Rotifers ; solitary specimens might 
indeed be captured, but for purposes of study solitary specimens are of very 
little service, as so many mishaps are sure to occur while attempting to isolate 
one and prepare it for microscopic investigation, that the first condition for 
success in this study is to have at hand several scores of the same creature. 
This will be readily understood when it is remembered that to study the 
internal structure of a Rotifer, it is necessary first to isolate an animal often 
less than 1-100 part of an inch, next to place it on a compressorium in a drop 
of water whose diameter shall not much exceed twice its own length, and 
then to hold the Rotifer without crushing it between two plates of glass, 
which for this purpose must be brought together within 1 -600th of an inch 
without touching each other. Should the plates of glass in the compressorium 
be not accurately parallel, the drop of water is certain to run aw ay from the 
Rotifer along the space where the plates more nearly approach one another, 
such space acting as a capillary tube, and thus the creature is killed, and all 
the time and trouble taken in isolating it, is lost. 
For these and other like reasons I had ceased to look for Rotifers in winter, 
but the accidental capture of a multitude of Synchoeta tremula, in a pond near 
Exmouth, in January, made me aware that I had come to a wrong conclusion ; 
no doubt Rotifers are scarce in the winter months, bnt they may be met with 
in sufficient numbers to make them available for study. 
I have thought therefore that it might be of service to others to mention what 
Rotifers I have met with at this time of the year, as well as the means I 
adopt for catching them. So far as my experience goes, all the winter Rotifers 
are free swimming ones ; it is true that I have met with Melicerta ringens late 
in November, and have then kept it eight or ten days more in captivity, but 
I never met with more than one at a time. As I have already said, I have 
taken Synchoeta (S. pectinata, as well as S. tremula) in hundreds in mid- 
winter, and not only at Exmouth, but also at Guildford and at Bristol. 
Triarthra longiseta swarmed in a pond at Portbury, up to the first week of 
December, at which time I paid it my last visit ; it is gone now, (22nd Jan. ) 
but 1 fancy that its disappearance is more owing to an alteration in the pond 
than to the time of year. Triarthra thrives in water dyed by manure to a 
decided brown colour, and when 1 diluted this water with rain water 
T found that I speedily lost all my specimens. Still there is no doubt a point 
at which the draining of manure into the pond kills Triarthra, and as the 
pond was very foul when I visited it last, and swarming with Paramecium 
(a sure sign of the abundant presence of decaying matter, and of the absence 
of almost all Rotifers except Hydatina,) I was not surprised to find my 
search unsuccessful. 
In Garraway's pond (in quite clear water) I took, this December, Polyarthra 
in great numbers, a few Synchoeta pectinata, a solitary Triarthra, (of what 
