WORMS, CRUSTACEA 379 



hours, or even two days, to complete, by which time the alcohol 

 and water will have passed off as vapour, leaving the worms 

 in viscid — almost pure — glycerine. They may then be exam- 

 ined in pure glycerine, or mounted in glycerine jelly as per- 

 manent slide-preparations. 



For rapid examination the specimens after fixation in 

 boiling 70 per cent, may be transferred to absolute alcohol 

 for thirty minutes, and then cleaned in " white " creosote. 



By this method the details of all small nematodes may be 

 seen perfectly. In the case of large forms, like some of the 

 Ascaridae, the details of internal anatomy can be made out by 

 transference from 70 per cent, alcohol to spirit, and thence to 

 creosote. The worms should be examined in creosote, and 

 then returned, for keeping, to 70 per cent, alcohol. 



Trematoda. — Small forms are examined whole, after clearing 

 in creosote, being transferred thereto from spirit. 



For examination of large opaque forms sections are neces- 

 sary ; for this rapid transference from formalin through acetone 

 direct to paraffin is suitable. 



When dehydration is complete, which may be tested by 

 transference to aniline oil (if this is done the specimen must 

 be returned to acetone) , transfer to a warm mixture of acetone 

 and paraffin, when infiltration is rapidly effected under an 

 exhaust pump. 



If it is desired to stain whole flukes they should be left 

 several days in very weak haematoxylin, and then differentiated 

 with weak acid. 



Cestoda. — Stain by immersion in weak haematoxylin after 

 fixing, or by direct immersion whilst alive in weak haematoxylin 

 and weak glycerine. Differentiate with acid after several 

 days, and mount according to general methods. 



Copepoda, Ostracoda, etc. — Preserve in 5 per cent, 

 formalin in sea water. They may either be kept 

 permanently in this fluid, or be subsequently trans- 

 ferred to 70 per cent, alcohol, the latter being perhaps 

 the better plan. 



For histological work, Hermann's fluid or corrosive 

 sublimate give good results. 



Amphipoda and Isopoda, Cirrhipedia, etc. — For 

 general purposes these may all be put directly into 



