94 NATURALISTS’ ASSISTANT. 
have not had the necessary experience to select for them- 
selves, hence the following words are written, and must 
not in any way be considered as an advertisement, except 
such as the merit of the various instruments themselves 
demands, | 
In the writer’s opinion, one of the best stands for all 
ordinary work is the smaller compound microscope manu- 
factured by Carl Zeiss of Jena and designated by him as 
“Va.” This stand alone costs ninety marks ($22.50) and 
when furnished with four eye-pieces and three objectives, 
A, C, D, F, giving powers of 20-1500 diameters, sells for 
three hundred and twenty marks ($80.00). This instrument 
will answer all the requirements of the naturalist or histologist 
in any special investigation. ‘The ordinary student, however, 
does not need these higher powers, and the same stand with 
three eye-pieces and the objectives “A” and “D” (1 inch 
and }) will answer all ordinary requirements and is sold 
for one hundred and seventy marks (about $42.50). Zeiss’s 
American agent is F. J. Emmerich, 138 Fulton St., New 
York, who imports, charging 50 per cent. to cover freights 
and duties. 
The instruments of Hartnack are fully equal in value to 
those of Zeiss and the differences in price are very slight. 
Geo. A. Smith & Co., 149°A Tremont St., Boston, are the 
American agents of Hartnack, or rather, of his successor, 
Prazmowski, and furnish his instruments at very reasonable 
prices. The stand III @ with two eye-pieces, and objectives 
4 and 7, giving powers from 50 to 450 diameters, is sold for 
