MATERIALS AND EQUIPMENT 5 



fashioned corked vials but they are so much better that they are worth the 

 additional expense. They should be available to the mounter in a great variety 

 of sizes. Where a number of very small objects is to be stored, it is convenient 

 to place each object in a little vial plugged with cotton and then to accumu- 

 late these vials in a larger 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 which is to be treated 

 is attached 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, one handles several slides at 

 one time, and for this purpose it is almost universal to use a coplin jar (Fig. 7). 

 These rectangular jars are furnished with a series of grooves which hold a num- 

 ber 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 thS sandwich into a groove, but this is 

 very unsatisfactory because reagents 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. 8) 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 convenient to use that it should be obtained 

 where possible. 



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

 which is required for ordinary purposes of slide-making. 



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

 pieces of equipment, such as microtomes, warming tables, paraffin, and embed- 

 ding ovens, which are part of the regular laboratory equipment. These will be 

 discussed in those parts of the book in which special preparations are described. 

 The student will also need an ordinary "dissecting set," but it is to be presumed 

 that he will have this from previous courses in the biological sciences which 

 he may have taken. If it is the intention of the instructor that the class prepare 

 hand sections, it will be necessary to have section-cutting razors, either avail- 

 able for issue or made part of the students' set of instruments. 



