12 BARKER,.ON A NEW MICROSCOPIC GROWING-STAGE. 
the ‘ Microscopical Journal’ have been usefully occupied in 
making known several valuable aids for this purpose; and as 
the growing stage lately brought under the notice of the 
Dublin Microscopical Club appears to present some advan- 
tages over growing slides at present in use, I have been 
induced to furnish a more ample description of it with an 
illustrative diagram. ‘To my view, a growing stage or slide 
should possess the following qualities :—1. It should be effi- 
cient, and not likely to go out of order, neither flooding the 
object and overflowing the stage, or drying up and allowing 
the air to get under the cover; (2) it should be easily cleaned ; 
(3) it should work well for at least a week, and even then 
should be capable of being suppled with fresh water without 
disturbing the object ; (4) it should enable the investigator 
when, in ordinary microscopic examination with a common 
slide and cover, he may have found something which he may 
wish to preserve moist, and observe at on a future occasion to 
do so with facility; (5) it should allow of the object being ex- 
amined at any time without displacement ; (6) it should permit 
the whole of the covering glass to be examined, and it should 
not be in the way of any other piece of apparatus ; and lastly, it 
should not be costly in price. Now, all these objects seem to me 
to be secured in the growing stage under consideration. The 
appliance would appear to be peculiarly valuable to those 
who would wish to watch the varying changes in microscopic 
alge, rhizopods, infusoria, rotifera, or anything requiring to be 
kept moist while under investigation. ‘lhe microscopist, in 
his usual investigations with an ordinary slide three inches by 
one inch, and with a common covering glass, frequently sees 
objects which he would wish to keep under notice for several 
hours, perhaps days or weeks, and this he will be enabled to 
accomplish by merely placing the slide on this stage, and at 
any time transferring it again to the stage of the microscope, or 
by putting the growing stage, with slide upon it, onthe stage of 
the microscope, the whole of the covering glass can be brought 
under inspection, so that no object which had been under the 
covering glass can escape observation. I have several rhizo- 
pods under notice at present for upwards of a week; and I 
have kept rotifera healthy for days in this appliance. The 
construction of this stage is so simple as to admit of any one 
expert in cutting glass to make it in a few hours; and I have 
drawn a diagram, to scale which will facilitate its construc- 
tion. 
A is a piece of stout glass from which is cut a large 
segment of a circle, C; B is a small flat bottle about two 
inches long, one inch wide, and about a quarter of an inch 
