Journal of Proceedings. 
xlix 
“From the platform in front of the Grotto, the point which gi'/es you 
the finest views of the lake and rich woods, I gathered a bunch of the 
Lemna which covers the water, and took it home, partly in the hope of 
finding it in flower and partly to examine the Diatomaceas and minute 
life among its tangled threads. I found the older rootlets covered with 
Cocconeis placentula, but no flower of the duckweed; however, I placed 
the plant in a saucer of water, and on looking over -it on Thursday had 
the great pleasure of finding Lemuel gibba in bloom. 
“ Boswell-Syme, in the last edition of Sowerby’s ‘English Botany,’ 
speaks of his never having discovered the flower in this species; and, as 
it is the rarest of the Lemnce, I have some hope that its occurrence in our 
neighbourhood in bloom may not be uninteresting to the botanical 
members of the Club, and that many others may share my enjoyment by 
procuring specimens for themselves.” 
Mr. Lister’s two ‘ notes ’ were illustrated by specimens and some 
beautiful coloured drawings of the plants referred to in all stages, 
executed by Miss Lister and himself. A cordial vote of thanks was 
accorded to him for his communications. 
Mr. C. Thomas, F.B.M.S., exhibited and described a new form of 
“Life-slide” for the microscope, a modification of the “ Hardy Vivarium,” 
enabling it to be readily applied to observation with high powers. The 
following is a description of the apparatus, to illustrate which Mr. 
Thomas has very kindly had the accompanying woodcuts engraved by 
Buffle:— 
A NEW FORM OF “ LlFE-SLIDE ” (“THOMAS’S VIVARIUM”). 
This vivarium was devised for aiding the microscopical study with 
all powers of the Infusoria or other minute life which exist so abundantly 
in our ponds and ditches. Many “life-slides,” “ compressors,” and other 
appliances have been used for similar purposes, but, so far as we know, 
none possess the advantages which are claimed for this contrivance. 
(1) Being composed entirely of glass and elastic bands, it is simple and 
inexpensive in construction; (2) for the purpose of being thoroughly 
cleaned after use it may be taken to pieces and put together again with 
ease and without the risk of breakage ; (3) the object under examination 
may be kept alive and in a healthy state for almost any length of time, 
and (4) may be viewed under the highest powers that are in any case 
necessary or suitable for thorough examination of the most minute 
organisms. 
The woodcuts, figs. 3 and 4, represent the vivarium of the full size 
suitable for use with the large microscope-stands of Messrs. Powell and 
Leland, Beck, or Boss; but, of course, it can be made of any dimensions 
to suit the size of the stage of the microscope employed. It is composed 
of two pieces of plate-glass, one of which has a circular hole in its centre 
(No. 1) or a segment of a circle cut out of its side (No. 2). A segment of 
an india-rubber ring is laid on the imperforated glass in the manner 
shown in the cuts, on this is placed a piece of very thin microscopical 
glass (or talc) of suitable size, then the perforated slide, the whole being 
firmly held together by a pair of elastic rings. We thus have a cell the 
upper side of which is thin enough to allow high powers to work through 
it, and which will hold fluid without leakage. The thin glass is so 
supported by the upper plate, with which it is in contact over the greater 
part of its surface, that there is practically no risk of breaking it in 
d 
