Ml ntlily Microscopical"! 
Journal, March 1, 1869. J 
New Groiving-slide. 
175 
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. 
I find that all the conditions prescribed by Dr. Barker as 
essential qualities in a growing-slide, are met by the simple piece 
of apparatus which I will now describe. 
Any ordinary glass-slide is pierced with a minute hole, at about 
three-tenths of an inch from the centre, on one side. When an 
object under investigation is put upon it immersed in water, the 
thin glass cover is so placed as to include this hole, which may be 
near the margin of the disk. When it is desired to keep the 
specimen moist while off the stage of the microscope, the slide is 
placed in the undermentioned piece of apparatus ; viz. a flat trough 
7 inches long, 2^ inches wide, with straight sides f of an inch high. 
In this the slide is placed, object uppermost, with one end (that 
nearest the hole) resting against the bottom of the vessel on one 
side, and the other end resting upon the edge of it. Sufficient 
water is put into the vessel to admit of the liquid reaching within 
a quarter or half an inch of the glass cover on the uppermost side, 
when it will be found that the water on the under-side reaches 
beyond the centre of the slide, and consequently beyond the hole 
with which it is pierced. In this state, the object will remain moist 
so long as the trough contains a sufficient quantity of water. When 
required to be placed on the stage of the microscope, the water is 
easily wiped off the sHde without any disturbance of the object. 
The trough may be made of tin plate japanned, or of glass, or 
of porcelain, and conveniently divided into six water-tight com- 
partments, whereby any number of slides up to six may be immersed 
in water without one interfering with the other. 
It is easy for the microscopist to provide himself with two or 
three dozen glass-slides, pierced as here described. If habitually 
used when examining aquatic objects, it will always be within his 
power to preserve in a moist state for an indefinite time any speci- 
men he desires to look into further. By cementing a glass ring 
upon the slide, a cell of any' depth may be employed. 
There is yet much to observe in regard to aquatic vegetation 
and animalcular life, which can only possibly be done by having 
the power to keep the object in a vital state for a considerable 
period, and under conditions which admit of the use of the highest 
powers of the microscope. A good growing-slide is therefore one 
of the most important pieces of apparatus which the microscopist 
can possess ; and I shall be glad if the contrivance here submitted 
meet this want, and serve as a stimulus to increased observation of 
cell-life in aquatic organisms. 
■ o 2 
