204 Modern Microscopy 



Fish Scales. — Scrape the fish from the head towards 

 the tail ; if scraped the other way, nearly all the scales will 

 be injured. Place the scrapings in a bottle of water, shake 

 well, pour off the water, and repeat the process until quite 

 clean. Examine with a microscope, and if you find that 

 the scales are not clean, pour off the water, add liq. potassae, 

 and soak for an hour or two ; then wash away the potash 

 with repeated changes of water, dehydrate in methylated 

 spirit, clear in clove-oil, and mount in Canada balsam. 



Sometimes fish scales buckle up in spirit, and they will 

 not lie flat. When this happens, put them into water 

 again, and soak a little while ; then place them on a slide, 

 and put another slide over them, press down until quite 

 flat, and tie the two glasses together with twine, and 

 place them in a vessel of methylated spirit to dehydrate 

 under pressure. This method will answer for all tissues 

 that have a tendency to twist during the process of dehy- 

 dration. 



Palates. — Dissect out, and soak in liq. potasste for a few 

 days. Wash well in water, spread out on a slide ; put a 

 piece of paper on each side of it to prevent crushing, and 

 place another slide over all in the same way as directed for 

 insects ; tie the glasses together with string, and place in 

 methylated spirit for an hour or two. Then remove the 

 palate from the glasses, and place it in clove-oil until clear. 

 Mount in Canada balsam. 



Sometimes it is very difScult to dissect out the palates 

 from small snails. This process answers just as well : Cut 

 ' off the head of the animal, being careful that you remove 

 the buccal mass with it, and place in liq. potassae for a few 

 days ; this will destroy all the soft tissues, but not the 

 palate or radula. Wash away the potash with repeated 

 changes of water, and proceed as directed above. 



Sections of hairs and quills may sometimes be cut 

 after soaking for a few days in methylated spirit ; but some 

 of the larger kinds, such as the whisker of walrus, will 

 require softening in potash. Place in liq. potassae for a few 



