1876.] Microscopy. 567 
into beads by the Nachet No. 5 objective of the San Francisco Micro- 
scopical Society, proves to be an anomalously easy shell. The objective 
fails on No. 19 of other slides by the same maker. Mr. Hyde is of the 
opinion that the resolved shellis a true Mitzschia curvula, although so ex- 
ceptionally easy that it is resolved by any good 4. 
Cot.ectine Diatoms. — Much of the difficulty of making reasona- 
bly clean collections of diatoms may be obviated by using Mr. John 
mayne’s method, which is described in Science-Gossip. A wide- 
mouthed bottle is attached to a cane in the usual manner, but instead of 
being open it is closed by a tightly fitting cork, through which are passed 
two glass tubes, terminating near the bottom of the vial. Externally 
one of these tubes is slightly bent sideways, so that its outer end can be 
easily approximated to a deposit of diatoms at the bottom of the water, 
while the other tube is bent at right angles immediately above the cork, 
and joined to a flexible rubber tube, which extends up to the handle of 
the cane. By compressing the rubber tube against the cane with the 
thumb of one hand, the bottle can be readily brought empty into position, 
when the calibre of the tube is restored by removing the thumb, and the 
pressure of water forces air out and water in, carrying the desired ob- 
jects with it. Should the water be too shallow to afford enough pressure, 
suction at the upper end of the flexible tube may be employed to exhaust 
the air, and thus secure a rush of water into the bottle, a glass tube or 
ball pipette serving as a mouthpiece. 
If too muddy, the gathering may be further cleaned by placing itina 
long bottle, the bottom of which is covered with black paper. Thus ar- 
ranged, and placed in the sunlight, the diatoms will soon free themselves 
m the mud and rise to the surface of the water. 
Micro-Puorocrapuy. — Dr. Edward J. Gayers, of Calcutta, in his 
Work at mitro-photography takes his position near the microscope 
Where it and the illuminating reflector can be manipulated with the 
steatest ease, while the image on the focusing screen is examined with 
‘small telescope consisting of a large opera-glass objective and a micro- 
Scopical ocular. 
: WATER Anatysis. — While there is still great doubt as to the exact 
influence or significance of forms perceptible by the microscope in drink- 
Ng-Water, there is no doubt a very general interest in studying and recog- 
nizing these forms. In such study good use may be made of Dr. J. D. 
onald’s work on Water Analysis, in which a large number of the 
more common forms of mineral and organic constituents are figured in 
rather crude but very suggestive and natural-looking pen-sketches, 
which are better as a means of recognition than the elaborate and flat- 
tering steel-engravings often used. Accompanying the drawings is a 
good Synopsis of the subject in a few pages of priut, which will be con- 
a even to those who have access to libraries of more elaborate 
orks, 
