Materials and Equipment 67 



screw-cap vial containing the preservative fluid. In this way, many 

 hundreds of minute specimens may be kept separate and safe for long 

 periods. 



Equipment for Handling Slides. Where the object to be treated is at- 

 tached to a slide, it is necessary to have special equipment to keep the 

 slides separate as they are put through the solutions. If only a single slide 

 is being handled, it is possible to use a vial, provided that the vial is more 

 than 1 in. in diameter. Almost invariably, however, several slides are 

 handled at one time, and for this purpose it is almost universal to use a 

 coplin jar (Fig. 78). These rectangular jars are furnished with a series 



Fig. 78. Standard coplin jar. 



Fig. 79. Rectangular slide jar. 



of grooves that hold a number of slides apart. Most coplin jars hold six 

 slides, but it is possible to obtain them to hold as many as 12. The number 

 of slides may be doubled by placing two slides back to back and sliding 

 this sandwich into a groove, but this is very unsatisfactory because re- 

 agents diffuse so slowly from between the slides. 



Coplin jars are made to handle only 3- by 1-in. slides. When one is 

 dealing with the larger size, it is necessary to use a rectangular jar ( Fig. 

 79) into which the slides are placed with their long edge downward. The 

 jar shown contains a removable glass rack, so that a number of slides 

 may be transferred from one jar to another without handling each one 

 separately. This type is a great deal more expensive than the conventional 

 rectangular jar with grooves down the side but is so much more con- 

 venient to use that it should be obtained where possible. 



A set of eight jars, either coplin or of the rectangular type, is the 

 minimum required for ordinary purposes of slide-making. 



In addition to the items mentioned, there are a large number of special- 

 ized pieces of equipment, such as microtomes, warming tables, paraffin, 



