OUR BOOK SHELF. 59 
clined to mat, touch with a hot pin or needle. Now bring the 
whole to a red heat for plenty of time to make the diatoms appear 
white and perfectly clean. 
On the centre of the glass slip place a tiny drop of old balsam, 
and with a pair of tweezers place the cover glass over it and hold 
the whole over the spirit lamp until a sea of the bubbles is seen 
underneath. Remove, and with a gentle pressure with a pin place 
the cover. The bubbles will all disappear and the balsam will be- 
come hard. To secure the diatoms all in the same plane turn the 
cover side down and leave in a warm place. 
The process of arranging diatoms is a simple one. The diatoms 
are picked one by one with a mechanical finger and placed where 
desired. 
To prepare the slide put it on a turn table, and with a pen make 
a small circle in the centre to guide in placing. On the other side 
of the ink ring put a tiny drop of pure distilled water, and with a 
small fragment of gelatine size it, so that when the diatoms are 
arranged breathing on them will bind them in the size. The best 
bristle that I have tried to use in the finger was recommended to 
me by C. M. Vorce, of Cleveland, who has done much excellent 
work with the microscope and with the mechanical finger. He 
uses a cat’s whisker, and I prefer it in most cases to any other. 
Prof. H. L. Smith uses a rubber tube with glass tips, through which 
he breathes gently to dislodge diatoms which adhere closely to the 
bristle. The breath is to moisten the slide and not to touch the 
diatoms until held to the side with the bristle, 
OUR BOOK SHELF. 
A Manual of the Infusoria. W. SAvILLE KENT, F.LS., F.Z.S., 
F.R.M.S. London: David Bogue. 1880. Pt. III. Pp. 289-432, 
with 8 Plates. 
Tue third part of this valuable treatise has at length appeared, and 
the general style deserves as much praise as the two former. 
In describing the animalculum eferomita lens, which is here 
identified with AZonas lens, the author offers suggestions which may 
possibly at no very distant date bring a rejoinder from Mr. Worthing- 
tonSmith. On page 293 we are told that “‘So remarkable a likeness 
subsists between the so-called bi-flagellate zoospores of the potato 
fungus Peronospora infestans figured by Mr. Worthington Smith in 
the Monthly Microscopical Journal for September, 1876, and the 
typical adult zooids of Heteromita lens as here figured and described, 
that the author is unable to repress a suspicion that these presumed 
