Journal of Applied Microscopy. 



627 



and the alkaline solution run under the cover-glass later on. For such cases 

 some students have found lactic acid helpful, and some recommend mounting in 

 oil. Thomas H. Macbride. 



University of Iowa, Iowa City, la. 



Slide-Labelling. 



A few years ago I found it desirable to be able to write in ink upon the sur- 

 face of the slides on which were temporary preparations of the plant parts which 

 I was studying. The oil or grease usually on slides makes writing upon them 

 difficult. Thorough cleaning of the slides with alcohol removes most of the oil, 

 and makes writing with a thick ink and not too fine pen quite possible ; but the 

 lines are coarse, and it is impossible to write much on such a slide. One of my 

 friends in Germany suggested painting the end of the dry slide, even without 

 any preliminary washing, unless the slide were stained, with a thin coat of very 

 fluid balsam. Such a coat quickly hardens enough to allow one to write upon it, 

 and by using a drawing pen one can write a great deal on the end of the slide, 

 in fact record there all the stages of the treatment to which the material has been 

 subjected. If it is desirable to make the writing permanent, another coat of 

 balsam after the ink is dry will make it as permanent as the preparation itself. 

 If permanent marking is desirable, it is preferable to use a rather thick ink, 

 Higgins's drawing inks for instance ; but a good writing fluid, such as Stafford's, 

 will serve the purpose admirably. In this case the ink must be allowed to oxidize 

 as well as to dry, before being sealed under the second coat of balsam. If only 

 temporary marking is all that is wanted, the anilin inks are preferable, since 

 they can be freely washed off. 



I mark all my preparations in this way now, using no gummed labels at all. 

 Slides thus marked can be washed in hot or cold water, with no danger of loosen- 

 ing or removing, or even of obscuring, the label. This advantage is offset, per- 

 haps, by the labels not being as generally legible as white paper ones, but if the 

 slides are held over white paper, the writing at once becomes clear and sharp. 



George J. Peirce. 



Fowl Fleas, to Mount. — These show the large muscles of thorax and legs 

 well. Kill and soak for three to six days in ether. Then soaked successively for a day 

 at a time in water, methylated spirit, absolute alcohol, and oil of cloves, and 

 finally mounted in balsam. Mount without pressure by placing three bits of thin 

 glass for the cover to rest on. 



