94 NATORAUSTS' 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 

 "Ya." 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 (I80.00). 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" (i inch 

 and I) 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 diflferences 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 a with two eye-pieces, and objectives 

 .4 and 7, giving powers from 50 to 450 diameters, is sold for 



