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NOTE ON THE MOUNTING OF SPIDER DISSECTIONS 

 AS MICROSCOPICAL OBJECTS. 



By Frank P. Smith. 



{Read November 23rd, 1909.) 



Cognisant as I am that my usual reply to inquiries concerning 

 my methods of mounting spiders has been for years past to the 

 effect that I do not mount them at all, I am rather diffident in 

 offering these few hints as to a means whereby slides may be 

 prepared in which the form and structure of the objects concerned 

 are faithfully preserved and exhibited. 



I must insist, at the outset, that to attempt to " clear " a spicier 

 with liquor potassae or any similar reagent is promptly to ruin it 

 as far as systematic work is concerned. The integuments of the 

 body are generally very deficient in chitin, and become hopelessly 

 transparent when treated with an alkali, whilst the male palpus, 

 whose form is of paramount importance in the identification of 

 species, is almost invariably distorted by any attempt at " clear- 

 ing." Apart from alkaline treatment, any pressure of the cover- 

 glass must be regarded as fatal. 



The chief use to which the arachnologist would put mounted 

 preparations would be comparison with other and usually un- 

 mounted specimens. For this reason it is obvious that every 

 endeavour must be made to preserve the mounted dissection in as 

 nearly as possible the same condition as the unmounted object. 

 It often happens that one possesses a solitary example of a rare 

 and obscure spider, and may have occasion to compare it, time 

 after time, with specimens more recently captured, or received 

 from correspondents. This means, under ordinary conditions, the 

 removal of the specimen from its tube of spirit, with much con- 

 sequent damage to legs and spines, all the more so on account of 

 the manipulation required to place it in the proper position for 

 observation in the saucer of spirit in which it is usual to examine 

 these creatures. The mounting of such a specimen, or of some 

 important portion of it, upon the orthodox 3x1 inch slip is 

 clearly an advantage provided that (1) it can be so mounted as 

 not to disturb the relative position of its component parts or alter 

 their form, (2) that it can be mounted permanently, or, if not, 

 that it can be expected to keep in good condition for a reasonably 



