ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
345 
aqueous solution. It is very suitable for use after hardening in 
formol. 
Microscopic Preparations of Copepoda.* — Copepoda are most easily 
collected, says Mr. C. D. Marsh, by means of a dredge, the mouth of 
which is covered with a cone of coarse wire gauze to keep out weeds, 
&c. For histological purposes, Copepoda are best killed by some one 
of the osmic acid preparations ; for other purposes alcohol is the best 
reagent. The best staining results are obtained by immersion in dilute 
picrocarmine for 1—3 days. For dissecting Copepoda, it is advisable 
to place the animals on a slide and replace the alcohol by glycerin. 
Farr ant’s medium, is recommended for mounting; the preparations can 
be transferred directly from the glycerin to the Farrant. 
(3) Cutting-, including- Imbedding and Microtomes. 
Rocking Microtome to cut Flat Sections.! — The Cambridge Scien- 
tific Instrument Company has produced a new pattern microtome to cut 
truly flat sections (fig. 91). It differs from the original rocking micro- 
tome in several respects. Larger sections can be cut, the tube holding 
the paraffin block being 30 mm. in internal diameter. The forward 
movement of the object towards the razor will allow of an object 12 mm. 
long being cut up without readjustment of the object-holder. A graduated 
Fig. 91. 
arc gives the thickness of the sections in thousandths of a millimetre. 
The object can be raised and fixed in a position clear of the razor, and 
the improved clamp is used for fixing the object-holder. The razor can 
be clamped either at right angles to the movement of the object or in a 
diagonal position for giving a slicing cut. The new instrument retains 
the essential features of the old rocking microtome,! but the arrangement 
is different, on account of the modification of the design. 
* Journ. Applied Microscopy, ii. (1899) pp. 295-6. 
t Cambridge Sci. Inst. Co.’s List, 1899, “pp. 83-4 (l?fig.). 
X Cf. this Journal, 1885, p. 549. , 
2 A 
1899 
