no rin-: microscoi'i:. 



make the Abbe Model Camera Lucidas, resolving Nosepieces, 

 and a reversible Compressor in aluminum. 



In the Object Catalogue they have considerably extended 

 the list of Bacteriological Specimens, and are now able to offer 

 medical men and Health officers very complete sets of Speci- 

 mens comprising all the principal subjects that are required 

 by students in England for the "Diploma of Public Health." 

 They have also revised their Botanical preparations so that in 

 every case the best example to illustrate a particular structure 

 may be given. Various new, popular, and show slides are also 

 included. 



This house has just received three awards at the World's 

 Fair, Chicago, being the highest conferred on any firm of optic- 

 ians, and making a total of 36 gold and other medals that have 

 been awarded to them at International Exhibitions. 



A New Book on Diatoms Proposed. — By request of the 

 author, Dr. A. M. Edwards, we invite subscriptions to Bacill- 

 iarise. It will contain a popular account of Diatoms in general 

 and the mode of collecting and cleaning their shells. Illustra- 

 ted, 100 pp. Price $3. Club rates to our subscribers $2.75. 

 From this price a further allowance of 25 cents will be made to 

 those who subscribe during November, payment to be made on 

 publication of the volume. 



Mosquitos. — There is no longer excuse for these pests exist- 

 ing as it has been found that a little kerosene oil poured upon 

 a pond's surface when they are germinating will destroy mill- 

 ions of them. Perhaps a few should be saved for mounting as 

 microscopical specimens. We do not want to actually extermin- 

 ate them. 



QUESTIONS ANSWERED. 



Note. — Dr. S. G. Shanks, of Albany, N. V., kindly consents to receive all sorts of ques- 

 tions relating to microscopy , whether ask<>d by professionals or amateurs. Persons of aU 

 f ades of experience, from the beginner upivard, are welcome to the benefits of this depa>- 

 ment. The questions are numbered /or future i eference. 



172. What is the theory and practice in the use of a mordant in 

 bacteriology ? Is it to fix the tissues or what is it for ? — Enquirer. 



