150 
NOTES AND MEMORANDA. 
On p. 59 (fiftli edition) he says, “ It is easily shown theoretically, 
that the picture of any projecting object seen through the microscope 
with only the ?'i^A^-hand half of an objective having an even moderate 
angle of aperture, must differ sensibly from the picture of the same 
object received through the Ze/i-hand of the same objective ; and 
further, that the difference between such picture must increase with 
the angle of aperture of the objective.” 
“ The stereoscopic binocular is put to its most advantageous use 
when applied either to opaque objects of whose solid forms we are 
desirous of gaining an exact appreciation, or to transparent objects 
which have such a thickness as to make the accurate distinction 
between the nearer and their more remote planes a matter of import- 
ance” (p. 69). 
At page 79 the writer draws attention “to two important advan- 
tages” he has found the binocular to possess. “ In i)iQ first place, the 
penetrating power or focal depth of the binocular is greatly superior to 
that of the monocular microscope;” and in the second place, when 
employed on objects suited to its powers, “ the prolonged use of it is 
attended with very much less fatigue than is that of the monocular 
microscope.” 
The Bevivification of Diatoms. — Mr. Habirshaw, of New York, 
states that “in 1871, Captain Mortimer brought from San Francisco 
in his ship a large bottle of diatoms (from fresh water), intending to 
study them during the voyage. When he arrived in England they 
were still alive, but afterwards dried up and remained in that state in 
his cabin until the summer of 1877 — a period of six years. Having 
found the old bottle, which we knew very well, we refilled it with 
water, and on examining it several days later we found some living 
specimens in it. At first this phenomenon inspired us with some 
doubts, but after a subsequent examination we came to the conclusion 
that these diatoms really were alive. The vessel has gone to sea 
again, and we await its return to verify anew the facts which we 
observed.” * 
A Method of Staining Bapidly. — I have long known that carmine 
staining acts quicker when the watch-glass containing the carmine 
and the section was not covered. But there is the disadvantage in 
this method, that particles of dust settle on the surface of the fluid, 
and are apt to adhere to the section on its being taken out. I 
recently tried warming the fluid, in order to overcome this drawback, 
and also because I thought that the more rapid evaporation of the 
carmine solution accelerated the colour being taken up, and I arrived 
by this means at surprisingly favourable results. 
After the first attempt had proved successful, I modified the 
procedure as follows ; — Over a water-bath (only partly filled) with a 
large opening, a wire netting is placed, upon which, as soon as the 
water begins to boil, the section is put in a watch-glass containing 
the carmine solution, and exposed to the action of the steam. In the 
course of from two to five minutes the sections are completely stained. 
They are then washed twice in distilled water, placed for a few 
minutes in common alcohol, and for the same time in absolute alcohol, 
‘Journal de Micrographie.’ 
