CHAPTER IV 



METHODS OF STUDY 



The treatment of material will vary much according to the 

 use to be made of it. If it has been collected and prepared pure- 

 ly for the purpose of making a determination of age for strati- 

 graphic correlation, it may be of no further value to the worker. 

 If the sample has been collected for scientific study, it will take 

 a very different course. In the next chapter, the methods used 

 in Economic work will be discussed and here the treatment for 

 scientific study only. 



Selecting and Mounting. If a fauna is to be worked up for 

 a scientific collection or for publication, it will be necessary to 

 pick out the specimens that are desired. In this work a binocu- 

 lar microscope with a large field and plenty of light is almost a 

 necessity. As most recent foraminifera and many fossil ones 

 are light colored the material should be loosely scattered over a 

 darker surface. Black is the most commonly used although at 

 least one of my students much prefers green. Blackened trays 

 may be made by blacking a shallow pasteboard tray with water- 

 proof ink. When this is scratched, another coat can be easily 

 applied. An excellent tray may be made by placing a plate of 

 glass over a piece of black velvet. This gives an intense black 

 surface against which specimens stand out with great distinctness. 

 It is best to have the specimens so scattered that individuals 

 stand out clearly. If the material is put on thickly, it is difficult 

 to distinguish forms clearly and the eye strain is much greater. 

 Lines in white may be ruled so that the black surface is divided 

 into squares if one wishes to search the whole area, and a 

 mechanical stage is of still greater help. One of the simplest 

 backgrounds may be made by exposing a photographic plate and 

 developing it so that a uniform black surface results. This may 

 be used for the bottom of a tray, or if corners are to be eliminated 



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