262 LABELING AND STORING PREPARATIONS [CH. AY 



remain the same while his knowledge, and hence his power of interpretation, 

 increase. They thus form the basis of further or more correct knowledge ; but 

 in order to be safe guides for the student, teacher, or investigator, it seems to 

 the writer that every preparation should possess two things : viz, a label and 

 a catalog or history. This catalog should indicate all that is known of a speci- 

 men at the time of its preparation, and all of the processes by which it is 

 treated. It is only by the possession of such a complete knowledge of the 

 entire history of a preparation that one is able to judge with certainty of the 

 comparative excellence of methods, and thus to discard or improve those which 

 are defective. The teacher, as well as the investigator, should have this infor- 

 mation in an accessible form, so that not only he, but his students can obtain 

 at any time, all necessary information concerning the preparations which serve 

 him as illustrations and them as examples. " 



\ 365. Labeling Ordinary Microscopic Preparations. The label should 

 possess at least the following information. 



The No. of the preparation, its name and date and the thickness of the 

 sections and of the cover-glass. 



C./.T 



DATE. 



FIG. 209. Example of a label of an ordinary his- 

 tologic specimen. (See also Fig. 159 for serial sections] 



fit 



% 366. Cataloging Preparations. It is believed from personal experience, 

 and from the experience of others, that each preparation (each slide or each 

 series) should be accompanied by a catalog containing at least the informa- 

 tion suggested in the following formula. This formula is very flexible, so 

 that the order may be changed, and numbers not applicable in a given case 

 may be omitted. With many objects, especially embryos and small animals, 

 the time of fixing and hardening may be months and even j'ears earlier than 

 the time of imbedding. So, too, an object may be sectioned a long time after 

 it was imbedded, and finally the sections may not be mounted at the time they 

 are cut. It would be well in such cases to give the date of fixing under 2, and 

 under 5, 6 and 8, the dates at which the operations were performed if they 

 differ from the original date and from one another. In brief, the more that is 

 known about a preparation the greater its value. 



% 367. General Formula for Cataloging Microscopic Preparations : 



1. The general name and source. Thickness of cover-glass and of 

 section. 



2. The number of the preparation and the date of obtaining and fixing 

 the specimen ; the name of the preparator. 



3. The special name of the preparation and the common and scientific 

 name of the object from which it is derived. Purpose of the preparation. 



4. The age and condition of the object from which the preparation is 



