The Microscope. 31 



ical research; the study of bacteria; solid and fluid tissues, etc. 

 The greater portion of the book is devoted to that most important 

 department of Microscopical technique — the use of reagents and 

 preparation of stains. Here will be found all needful data regard- 

 ing these, and especially as employed in bacteriological investigation. 

 The chapter on bacteria (accompanied by an admirable plate) is one 

 of the most concise and clear that we have seen on the subject. The 

 publishers have presented the volume in most attractive shape. 

 Investigators will find it invaluable in their work. 



CORRESPONDENCE AND QUERIES. 



Editor Microscope: 



Microscopists who keep up an extensive exchange of slides find 

 it rather expensive to pay fi'om $4 to $7 per gross. The bulk of the 

 expense involved lies in finishing the edges. Please allow me to 

 suggest an idea gratis, which I hope opticians or glass manufac- 

 turers will take hold of, i. e., to stamp or press slides out, from one 

 to five gross in one impression — slides with a nicely beveled edge, 

 straight , flat surface, true to gauge. I believe this process would 

 reduce the cost of slides one-half, if not two-thirds. I have seen, 

 articles of glassware stamped out with the nicest perfection. The 

 first expeQse is the making of the die or mould to press them in, but 

 this should be no obstacle. In nearly all good glassware you will 

 find a quality of glass — white and clear, which I think would make 

 excellent slides — much better than crown glass. Who will act in 

 this matter ? J. D. BECK. 



Liberty, Pa., Oct. 24, 1886. 



M. S. B. — You will have no trouble with the sections embedded 

 in celloidin if you clear them up in oil of origanum rather than that 

 of cloves, as the former causes no curling of the celloidin. 



S. P. C — The trouble with your specimens seems to be that 

 they have been preserved too long in the dilute alcohol, and have 

 undergone putrefactive softening in the interior from being too 

 large for the alcohol to penetrate them. Cut your future specimens 

 into ^ inch cubes and immerse, from the start, in 95 per cent, alcohol. 



F. B. S. — Canada balsam is to be preferred to dammarlac as a 

 mounting medium, for not only does it harden more rapidly and 

 firmly, but air bubbles, inadvertently introduced into it, are absorbed 

 or pass out, which is not the case with dammar. Glycerin mounts, 

 however well protected by rings, cannot be looked upon safely as 

 being permanent. 



