Collection and Preparation. 1 1 



purpose. Higher powers are seldom required. The more delicate 

 hairs and spinnerets are sometimes so very transparent that 

 staining is necessary to make them more visible. For this purpose 

 an alcoholic solution of magenta, or some other aniline dye (or 

 even ordinary red ink), may be run in under the cover-glass, and 

 the slide put aside for twenty-four hours. Finally, the object 

 should be washed in clean alcohol to remove the superfluous 

 colour, and permanently mounted for microscopic use. I would 

 strongly recommend the staining of all the more delicate objects. 

 Unsuspected characters will often be revealed by this means, and 

 it will help to clear up many doubtful points. If there is any 

 question about the number of joints in an antenna, or the hairs 

 on the anal ring, the addition of the stain will usually make them 

 perfectly distinct. 



Canada balsam is usually advocated for mounting prepared 

 specimens of Coccidae. I find, however, that this medium has 

 the property of making delicate objects so very transparent that 

 much of the minute detail is lost or extremely difficult to de- 

 cipher unless they have previously been deeply stained. Balsam 

 has also the disadvantage of darkening with age. Glycerine 

 jelly or Farrant's Medium — personally I prefer the latter — have 

 not these faults ; and the object may be transferred direct from 

 the alcohol to either of these mixtures. Care should be taken 

 that no more of the medium is used than will suffice to fill 

 the very small space between the cover-glass and the slide ; 

 otherwise it will be found difficult to seal up the mount satis- 

 factorily. If the Canada balsam method is preferred, the 

 specimen must be transferred from the alcohol to oil of cloves 

 or cedar-wood oil, to remove all traces of the spirit ; after which 

 it may be mounted in balsam in the usual way. Whichever 

 preparation is adopted, the best results will be obtained by 

 placing a drop of the medium on the cover-glass and lowering it 

 on to the object. After placing the cover-glass in position the 

 medium can be induced to spread evenly, and any air-bubbles 

 can be expelled by gently heating the slide over a spirit-lamp. 

 Canada balsam will set quite hard and requires no final sealing ; 

 but with the glycerine preparations a ring of asphaltum or 

 caoutchouc cement must be formed round the edges of the cover- 

 glass, to prevent subsequent evaporation or exudation of the 

 medium. No doubt, in some particulars, Canada balsam has its 

 advantages. Such mounts are more permanent and less liable 



