174 
Ntw Growing-slide. 
fMonthlv Microscopical 
L Journal, March 1, 1869. 
IV. — On a New Growing-slide. By C. J. Mulleb. 
Microscopical observers, whose attention has been bestowed upon 
animalcular hfe and cryptogamic aquatic vegetation, have long 
sought for some simple means of preserving the subject of investiga- 
tion moist and in a state of vitality during prolonged examination 
under the microscope. The old fashioned polype-trough, the live- 
cage, the sunk-cell, were the earliest contrivances for this purpose. 
Kecently, Professor Smith, of Kenyon College, Ohio, introduced to 
the notice of microscopists a growing-slide, described in the ' Annals 
of Natural History,' Nov. 1865, a modification of which was sug- 
gested by the late Mr. Eichard Beck, in a paper read before the 
Microscopical Society of London, on Dec. 13, 1865 ; and still later, 
Dr. Barker, of Dublin, proposed a piece of apparatus, by which an 
object placed upon an ordinary glass-slide might be kept moist, with 
very little attention, for a considerable period. 
To the American growing-slide, several serious objections have 
been advanced. First, that it is difficult to fabricate, except by 
experienced hands ; 2ndly, that it is impossible to clean it, except 
by pulling it to pieces and recementing the parts ; 3rdly, that the 
thickness of the cell interferes fatally with the use of various 
sorts of illumination below it, when objectives of high power are 
employed. 
Mr. Beck's contrivance ofiers a partial remedy for the incon- 
venience last named, but does not wholly succeed, and moreover 
the supply of air and water is limited, besides which the apparatus 
is such as no amateur could make himself. 
Dr. Barker's invention seems to me to be rather too elaborate 
and costly a contrivance for the purpose required. It is even more 
difficult of fabrication than the American apparatus; and it is 
evident that an observer would require at least half-a-dozen of these 
growing-stages to help him in his observations — one stage being 
good for only one slide at a time. This gentleman, in his paper on 
the subject in the ' Quarterly Journal of the Microscopical Society ' 
for January, 1867, has admirably stated the qualities which a good 
growing-slide should possess ; viz. 1. It should be efficient and not 
likely to go out of order, neither flooding the object and overflowing 
the stage, nor 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 supplied 
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 on a future occasion, to do 
so with facility. 5. It should allow of the object being examined at 
