LABELLING MOUNTED OBJECTS 523 



objects are mounted, or to the implements used in the manipulations, 

 any extraneous particles are brought into view with the object itself. 

 Some such will occasionally present themselves, even under careful 

 management ; especially fibres of silk, wool, cotton, or linen, from 

 the handkerchiefs, &c., with which the glass slides may have been 

 wiped ; fibres of the blotting-paper employed to absorb superfluous 

 fluid ; and grains of starch, which often remain obstinately adherent 

 to the thin glass covers kept in it. But a careless and uncleanly 

 manipulator will allow his objects to contract many other impurities 

 than these ; and especially to be contaminated by particles of dust 

 floating through the air, the access of which may be readily prevented 

 by proper precautions. It is desirable to have at hand a well-closed 

 cupboard furnished with shelves, 'or- a cabinet of well -fitted drawers, 

 or a number of bell-glasses upon a flat table, for the purpose of 

 securing glasses, objects, &c., from this contamination in the intervals 

 of the work of preparation ; and the more readily accessible these 

 receptacles are, the more use w r ill the microscopist be likely to make 

 of them. Great care ought, of course, to be taken that the media 

 employed for mounting should be freed by effectual filtration from all 

 floating particles, and that they should be kept in well-closed bottles. 



Labelling and Keeping Mounted Objects. The object of labels 

 on mounted objects is of course to give clear and instant indication 

 of the nature of the mount. But we must, if our cabinet shave any- 

 thing like scientific pretensions, not only know what the object may 

 be, but some (perhaps many) other particulars about it. In fact, a 

 thoroughly scientific cabinet must not rely on the labels on the 

 mounts for all the information which it is desirable and even 

 essential to have concerning them. One of the desiderata of every 

 label should be the presence of a number, and this number should be 

 at once placed in a book, arranged in columns to suit the requirements 

 of the student, and most of the details should be placed in this book 

 in association with the number. 



For this to be of permanent service, however, the label 011 which 

 the number is placed should be as permanent and immovable as the 

 slip itself. We know of cabinets in which only numbers are 

 marked on slides, and all details are recorded in ' the book.' We 

 do not advise this ; but all who keep cabinets know how in the course 

 of years ^paper labels become displaced and lost, and in many 

 instances the value of slides is greatly diminished. 



What is wanted is a permanently fixed label, capable of receiving 

 the chief points of character as well as the name and number of an 

 object. 



The present Editor has found the following plan to be hitherto, 

 after twenty-three years' trial, quite faultless. 



Let the slips which are to be used for mounting have the two 

 ends of the upper surface finely ground ; at one end the ground 

 surface may be three quarters of an inch, and at the other end half 

 an inch. On the ground surface we can write with a hard pencil as 

 clearly and sharply as with a fine pen on cardboard. 



On the broader ground surface let the principal facts as to the 

 nature of the object be written and the number of the slide with a 



