190 



Specific Examples of Slide Making 



> 



135 



136 



Figs. 135 and 136. Good and bad mounts by the method described in this example. 



Fig. 135. An excellent wholemount of a liver fluke. Notice at 1 that at least part of 

 the uterus has been properly cleared and that at 2 there is good detail in the genital 

 region. There is also at 3 a clear demarcation between the testes and yolk glands. 

 Fig. 136. A thoroughly bad mount. All the good features shown in Fig. 135 are lack- 

 ing. In addition, the specimen is contracted and distorted, indicating imperfect nar- 

 cotization and imperfect flattening. There is also a large lump of dirt at 4. 



The selection of fixative must rest, of course, in the hands of the operator, 

 but the author's preference is for the mercuric-acetic-nitric mixture of 

 Gilson. This has all the advantages in sharpness of definition given by 

 mercuric fixatives, and the addition of nitric acid appears to render 

 the flattened worms less brittle in subsequent handling. Whatever fixative 

 is selected, the sheet of filter paper is saturated thoroughly with it, and 

 the anesthetized worms are removed from the physiological saline and 

 laid out one by one about 1 in. apart on the paper. This must be done as 

 rapidly as possible to prevent fixation from taking place before an addi- 



