ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 



158 



Mounting Fluid for Algse.* — For preserving the cell-contents and 

 the natural colour and form of desmids, volvox, and other alg83, 

 G. W. Morehouse finds a mounting fluid made as follows to act well : 

 Dissolve 15 grains of acetate of copper in a mixture of 4 fluid ounces 

 of camphor water, 4 fluid ounces of distilled water, and 20 minims of 

 glacial acetic acid ; add 8 fluid ounces of Price's glycerine, and filter. 

 When sections of plant-stems, or other vegetable specimens, are 

 mounted in this fluid, the protoplasm is preserved. If, in any case, 

 it is thought desirable to increase or diminish the specific gravity of 

 the preservative, the proportion of glycerine may be changed. Used 

 as above, or modified as indicated, he thinks it also a trustworthy 

 medium for mounting infusoria and the softer animal tissues. 



Mounting Diatoms in Series.f — P. Francotte has applied Gies- 

 brecht's method | of mounting sections in series to the mounting of 

 diatoms. The slide is coated with the solution of shellac in alcohol 

 washed over with oil of olives or creosote, and the diatoms, previously 

 placed in absolute alcohol, arranged in order. The slide is then 

 warmed, and the oil of cloves or creosote evaporated. 



Schallibaum's process § for sections would also be available for the 

 same purpose. 



Registering Micrometer-screw to the Thoma Microtome. ||—^ 

 Dr. C. 0. Whitman gives the following more detailed description of 

 this screw, which we described at pp. 914-5 of vol. iii. (1883) from 

 the original article of Andres, Giesbrecht, 

 and Mayer, the designers of the arrange- 

 ment for regulating its movement. This 

 arrangement consists of a spring which, 

 after a given number of divisions of the 

 drum, registers to the ear and finger of the 

 manipulator the number of micromilli- 

 metres which the object has been raised. 

 The intervals between the registering 

 clicks can be varied by means of a vernier- 

 like adjustment of the two iaalves of the 

 drum, so as to equal an entire revolution 

 of the drum, or only 1/15, 1/3, or 1/2 of 

 a revolution. 



An examination of fig. 27, which illus- 

 trates the new form of the drum, will show 



how the intervals are regulated. The drum is composed of two 

 symmetrical halves, A B and A' B', so closely opposed that the 

 dividing line (dotted in the figure) is scarcely visible. The periphery 

 of each half is composed of two zones of unequal radii. The large 

 zones, B and B', are in apposition, and together form the graduated 



* Amer. Mon. Micr. Journ., iv. (1883) pp. 234-5. 



t Bull. Soc. Belg. Micr., x. (1883) pp. 43-8. 



X See this Journal, ii. (1882) p. 888. 



§ See this Journal, iii. (1883) p. 736. 



11 Amer. Natural., xvii. (1883) pp. 1313-4 (1 fig.). 



