4 MATERIALS AND PROCESSES OF SLIDE-MAKING 



1/2 -in. size is much more convenient and is quite large enough for the major- 

 ity of wholemounts. Square coverslips come in the same sizes as do the circular 

 ones. The choice between circular and square depends entirely on the prefer- 

 ence of the mounter. Square coverslips are a trifle easier to handle, but round 

 coverslips have the advantage that one can "ring" the slide if one is making 

 fluid or dry mounts. These types of mounts, however, are not described in this 

 book, for they are unsuitable for elementary students. Rectangular coverslips 

 intended for use on 3- by 1-in. slides are always 22 mm. across their narrowest 

 dimension and may be obtained 30, 40, or 50 mm. in length. It is rarely wise 

 to use a coverslip longer than 50 mm., for insufficient space will be left on the 

 end of the slide for the application of the label. Coverslips intended for use 

 with iV^-in. slides are usually 35 mm. on their shortest dimension, and those 

 intended for use with 2-in. slides are generally 43 mm. on their shortest dimen- 

 sion. Coverslips for use with larger slides are almost invariably 50 mm. long. 

 Containers for Handling Objects. Objects intended for microscopical 

 examination have to go through a variety of processes, which are described in 

 the next few chapters. Either the object may be put through these processes 

 and subsequently mounted or it may be attached to a slide and the slide put 

 through the processes. In either case a special container is required. Small objects 

 are usually transferred between solutions either with a pipette (Fig. 1) or a 

 section lifter (Fig. 2), the choice between the two depending upon the size 

 and shape of the object. Where the object will stay for only a short time in a 

 solution, it is customary to employ Syracuse watch glasses (Fig. 3). These are. 

 called watch glasses because they have replaced the more conventional type of 

 watch glass in laboratory technique. They have the advantage over the con- 

 ventional type of being less easy to upset, and are so shaped that they may be 

 stacked one on top of the other, both for storage and prevention of too-rapid 

 evaporation of the contained solutions. They would be far better called Syra- 

 cuse "dishes," but the name watch glass is still in customary use. Embryological 

 watch glasses (Fig. 4) are used less for soaking objects in various solutions than 

 for embedding objects in paraffin. They are very convenient for the latter pur- 

 pose. They may also be used in place of Syracuse watch glasses and have the 

 advantage that they are provided with a cover which prevents evaporation of 

 the contained solutions. They are not, however, so convenient as the conven- 

 tional stender dish (Fig. 5), which is furnished with a round, ground-on cover. 

 If this cover is touched with a little petrolatum, it is possible to keep alcohol 

 for several days in the dish without loss. When an object has to be stored for 

 any length of time in a fluid, it is much better to use a vial (Fig. 6), the type 

 shown having a screw cap of plastic. These are more expensive than the old- 



