COLLECTION OF OBJECTS 525 



merely the number of the slide and the letter and page of the special 

 notebook wherein all about the slide will be found. Thus : 



'649, F 127.' 



This means that in notebook F on page 127 we shall find an 

 account of slide No. 649. 



On turning to notebook F we find (say) that the subject is 

 geology. The following will be a facsimile of the page : 



Slide No. 649 127 



Section of porphyry from Peterhead, Aug. 1886. The quartz 

 crystals in this section have minute cavities containing a liquid, CO 2 . 

 In each cavity there is a bubble ; some of these bubbles are ex- 

 tremely minute, and exhibit rapid Brownian movement. A good 

 example of which is 



No. 2 (referring to a second microscope when used), 46-51. 



A large bubble with no Brownian movement. 



No. 2 (microscope), 44-47. ' 



Section too thick for oil immersion. 



Best seen dry J '95 N.A. deep eye-piece ; condenser aperture 

 6 N.A. 



At the back of each notebook there is an alphabetical index. 

 In this instance if we look up ' Porphyry' we shall find 127, and if 

 we look up ' Quartz (cavities in) ' we shall find 127, and if we look up 

 ' Carbonic acid (in quartz)' we shall find 127, and if we look up ' Bubbles 

 (in quartz)' we shall find 127. 



By this means the collector can find a slide if he know the 

 subject, and also the subject if he have the slide. 



This is the only scientific method we know of dealing with a 

 microscopical collection ; it is one of the greatest practical mistakes 

 to make the cabinet its own index. It always ends in supreme 

 confusion. But for the purposes of the man of science a large 

 cabinet made with a view to the reception of his own slides is far 

 preferable. The majority of slides are 3x1 inches ; but all are not 

 some geological and mineralogical sections, sections of coal, &c., are 

 often much larger. Many objects, again, are in deeper cells than 

 the ordinary cabinet drawer or slide-box will admit of; all this may 

 be provided for, and if money be not a special object, a design with 

 two or three special and smaller cabinets may be made for the 

 reception of special series of mounts. 1 



COLLECTION OF OBJECTS. 



A large proportion of the objects with which the microscopist 

 is concerned is derived from the minute parts of those larger 

 organisms, whether vegetable or animal, the collection of which does 

 not require any other methods than those pursued by the ordinary 

 naturalist. With regard to such, therefore, no special directions 

 are required. But there are several most interesting and important 

 groups, both of plants and animals, which are themselves, on account 



1 It will be understood that there are many forms of cabinet which space prevents 

 our describing ; they are made suitable for the pocket, for postal transmission, &e., 

 and may be readily seen at the opticians'. 



