60 THE AMEEICAN MONTHLY [March, 



will pay to clean all slips by the chemical instead of mechanical method. 

 A good quality of cement is also essential to success. — C. M. V. 



MISCELLANEOUS. 



Marine Alga ^Ptilota -plumosa). — This preparation in balsam 

 shows the object very much as a well-preserved mummy shows the 

 original. If softened and washed in sea-water, and mounted in hard 

 glycerine jelly, it would show the object as it is in life, with perhaps the 

 loss of a little color. — J. D. K. 



How to Look at It. — A nice slide ; but it would be better if we 

 were told whether to use a three, two, or one-inch objective, and also 

 whether by dark field illumination or otherwise. Full descriptions add 

 greatly to the interest of any slide. — J. F. B. 



Aniline green that will stand dehydrating with oil of cloves, etc., I 

 do not believe can be found ; but I would like to have some one tell 

 me why so many insist on mounting wood sections in balsam. Balsam 

 mummifies everything, while a properly made glvcerine jelly preserves 

 protoplasm and differentiates perfectly. — J. D. K. 



Alcohol. — -From the appearance of the mount I should say that the 

 alcohol used for dehydrating was of too low a grade, and that a precipi- 

 tation has occurred. This is liable to happen with all the olio-resins. 

 If the water is present in a large degree we shall have instead of a pre- 

 cipitation of resin an emulsion of the oil and resin. — H. AI. L. 



Staining. — This specimen should have been double stained after the 

 section was cut As it now is, it merely shows the blood-vessels. 

 Staining would have brought out the cells of the urinary tubes, and in 

 connection with the injected blood-vessels have made not only an in- 

 teresting but an unusually instructive specimen ; for, being a complete 

 section, all of the structural elements are contained in it. — H. M. L. 



Fading. — This slide (desmids, etc., in glycerine) is over a year 

 old and much faded. It would have been a fine slide if the color could 

 have been held in it. Eosin would have done it, but it might have 

 made a very dark slide. — « * * 



Fancy rings do not add anything to the value of the mount ; instead, 

 the cover should have been secured by a heavy ring of some tough ce- 

 ment. When the cover is attached by balsam alone, a slight jar is often 

 sufficient to detach it ; especially is it so in a case of this kind when the 

 slide is being constantly knocked about in the mails. — H. M. L. 



Unground edges should not be put in Club boxes (nor used at all) 

 unless the slip is covered with paper. Careless packing of the slides 

 has planed off the cement from some of the other mounts by means of 

 the sharp-cut edge of this slide. — C. M. V. 



Crushing. — Before mounting the contributor should have cemented 

 three small pieces of cover-glass on the under side of the cover. This 

 would have obviated all the crushing of choice forms so noticeable in 

 this otherwise good slide. Diatoms are also often crushed by the con- 

 ti'action of the balsam after mounting. — * * * 



No Cell. — This slide is mounted without a cell excepting what is 

 built up around the cover ; therefore it will not bear throwing around 

 a great deal, but it will smile on you if you treat it kindly. — * * * 



Cements. — I would like to suggest to * * * that he discard 

 home-made cements, and obtain one or two bottles of King's micro- 



