1880.] 



MICKOSCOPICAL JOURNAL. 



95 



water) sometimes abundant. Swims 

 with a wagging motion. The fla- 

 gella become readily attached ; they 

 are not easily made visible, on ac- 

 count of their great length. 



6. Gen. Tetramitus, Perty. Body 

 conical, pointed behind, with four 

 moving ilagella on the blunt, ante- 

 rior end. 



T. rostratus, P. Colorless, pear- 

 shaped, on one side elongated like 

 a beak, 0.02. 



7. Gen. Uvella, Ehr. Animal in 

 spherical, moving families 0.06 d. 



U. glaucoma, Ehr. Individuals 

 egg-shaped, 0.01 1. without pig- 

 ment spot, but with many nuclei, 

 color bluish. In foul infusions. 



IT. mrescens, Duj. Greenish, 

 similar to the preceding, and differ- 

 ing from Hydromorxnn uvella. 



8. Gen. AnihojpTiysa, Bory. Ani- 

 mals in dichotomously-branched 

 stems, fixed, or swimming as flocks. 



A. Mulleri, B. Stem brown. 

 Individuals attenuate in front, 0.01 

 1. Stems 0.1—0.2 1., 0.03 thick. 



The Preparation and Mounting 

 of Microscopic Objects. 



II. DRY-MOUNTING. Dry objccts 

 are mounted both transparent and 

 opaque. When the objects are quite 

 large it is best to mount them 

 opaque, but when they are small, 

 or when they are to be examined 

 with the lieberkuhn, or with the 

 paraboloid, they must be mounted 

 accordingly. Many of the more 

 delicate diatoms should be mounted 

 dry, as transparent objects, for their 

 delicate markings might be entirely 

 lost in balsam or otlier media. 



The best way of mounting an 

 object, should always be deter- 

 mined by a preliminary examina- 

 tion with the microscope. It will 

 not do to assume that an object 

 will look well dry, unless we exam- 



ine it in a perfectly dry condition ; 

 for many objects will shrink and 

 shrivel during the drying process, 

 and no permanent mounts can be 

 made unless the objects are perfectly" 

 dry. 



For dry -mounting a cell is always 

 necessary, and these are made in 

 various ways. 



1. To mount diatoms, or very- 

 minute objects, dry and transparent. 



Take a perfectly clean slide, select 

 a suitable cover-glass (a ^-inch is a, 

 good size), and make a ring on the 

 slide with the turn-table, just sa 

 large that its outer edge will extend 

 beyond the edge of the cover-glass,, 

 when the latter is applied. This 

 ring may be made of benzole-bal- 

 sam, of asphalt, or of various other 

 cements, but the best of all, because 

 it dries so rapidly, is shellac. In 

 all cases the cement must become 

 entirely hardened, before the mount- 

 ing is carried any further, otherwise 

 the cement is likely to creep under 

 the cover, after the mount is finished 

 and laid away. For this reason, 

 especially if the cell need not be 

 made very thin, it is often advisable 

 to make the ring out of sheet wax, 

 which can be attached to the slide 

 by gentle warmth and pressure, or 

 turned up on the slide by Dr. 

 Hamlin's method (p. 46) ; very thin 

 sheet caoutchouc may also be used, 

 punching out rings of the right 

 size and attaching them by heat,, 

 and this material is excellent for 

 diatoms. It is advisable to keep a 

 number of prepared cells always 

 ready. 



The objects should now be placed 

 in the cells, a thin coat of cement 

 — benzole-balsam, asphalt or shellac 

 — should be applied to the cell, the 

 cover-glass immediately pressed 

 down evenly, after which the slide 

 can be set aside until a sufficient 

 number have accumulated to under- 

 go the finishing operations together. 



