50 Mr. H. J. Carter on the Ovigerous Layer of 
Now remelt the material on the glass slide as before ; and 
when sufficiently fluidified to present a uniformly level surface 
(but not burnt, for this would destroy the tenacity of the 
cement and thus give it a crispness which, by cracking, would 
defeat all attempts at further reduction), quickly transfer the 
warmed slice (which should now be close at hand) to it, 
while with a little pressure the ‘ smoothed”’ surface is brought 
into direct contact with that of the glass. Thus let it remain 
on the table where thisis done until the glass feels cold to the 
touch. 
After this reduce the slice to the thinness of a wafer over a 
very fine vertical rotating grinding-stone, or on a copper plate 
with emery powder and water, horizontally. 
Now wash it well in water, and, placing the slide on a 
piece of buckskin leather spread on the table or over a level 
surface (to keep it from slipping) with the slice uppermost, 
continue the reduction in water with a piece of very fine 
siliceous limestone, that may be obtained from a statuary, of 
a convenient form (that is, one which will admit of the surface 
of the slice coming into direct and continuous contact with 
that of the limestone), with which it should be horizontally 
rubbed until reduced to the required thinness, which must_ be 
ascertained by repeatedly transterring the slice to the field of 
the microscope with an inch object-glass and high ocular, 
The nearer this thinness is approached the oftener this trans- 
fer should be made, washing the slice by dipping the slide 
into a bowl of water each time that it is examined. 
When sufficiently reduced, wash the slide as before, and 
stand it up to drain until the slice is perfectly dry. Then 
cover with benzol, followed by balsam and thin glass, for 
preservation and more deliberate examination. 
I make no apology for introducing these remarks, as the 
“ process,” although open to criticism and improvement no 
doubt, answers the purpose; and while inexperienced I 
myself should have been very glad of such aid. Dr. Holl 
suggested to me the use of shellac, which is the most valuable 
hint that I have received. 
1V.—On the Presence of Starch-granules in the Ovum of the 
Marine Sponges, and on the Ovigerous Layer of Suberites 
domuncula, Nardo. By H. J. Carter, F.R.S. &e. 
Ir was but a short time since that I pointed out another in- 
stance of a structure like thai of the cellular tissue of plants, 
