Principles 



JELLY MOUNTS 



47 



jelly, and thus necessitates the glycerol 

 technique described in Chapter 3. The 

 author prefers to transfer objects from 

 95% alcohol to 70% alcohol and then to 

 add, by such stages as are necessary, 

 enough glycerol to this mixture to insure 

 that, when the alcohol has been removed 

 by evaporation, 50% glycerol will remain. 

 The two great difficulties in mounting 

 material in these media are first to arrange 

 the object on the shde before the jelly has 

 time to solidify, and then to get the cover- 



in which they are left until they are thor- 

 oughly permeated, and then placed in a 

 stender dish on top of a water bath, seen in 

 the left background of the picture. On this 

 water bath, which is held about 10°C. 

 above the melting point of the jelly, there 

 is also placed the bottle containing the 

 mounting medium and as many sHdes as 

 will be required. A shde is taken, a molten 

 drop of the medium placed on the warm 

 shde, and the object to be mounted re- 

 moved with a pipet and placed in this 



Fig. 22. Layout for jelly mounting. 



slip into place without disarranging the 

 object. The writer has invented a tool for 

 overcoming these troubles, the use of 

 wliich will be described in some detail. 

 The layout, when one is mounting a num- 

 ber of objects, is shown in Fig. 22; the only 

 object not commonly found in laboratories 

 is the special tool shown in the left hand in 

 the picture. This device is a short length 

 of ^^-inch aluminum rod flattened at one 

 end and rounded at the other. This alumi- 

 num rod is screwed to a short length of 

 brass tube which terminates in a wooden 

 handle. The procedure in mounting small 

 objects is as follows. The objects them- 

 selves are accumulated in 50% glycerol, 



drop. The shde is then removed from the 

 water bath and examined under a micro- 

 scope while a warmed needle is used to 

 push the object into the required position. 

 Make sure that it is in contact with the 

 slide and that there is a considerable 

 amount of jelly above it. In the center of 

 the picture will be seen three slides which 

 have so been treated and laid on one 

 side until the medium has hardened. As 

 many slides as are required may be 

 treated in this manner so that one has a 

 series of preparations, each of which con- 

 tains a domed drop of solid jelly with the 

 object lying in the required position at the 

 bottom of it. Now take a cover glass of the 



