SPIDERS : THEIR STRUCTURE AND HABITS. 63 



fluid. If, however, the tissue has been hardened in Bichromate, 

 or in Chromic Acid, they must go into a solution of Carbonate of 

 Soda, before staining. 



Haematoxylin stain is made by boiling 



Extract of Hcematoxylon ... ... i part; 



Alum ... ... ... ... 3 parts; 



Water ... ... ... ... 40 „ 



filtering when cold, and adding to this fluid methylated spirit 5 or 

 6 parts. This stain has some advantages over that made with 

 carmine, but ink is a very fair substitute for either. 



Watch-glasses for holding the sections in the various re-agents, 

 viz : — methylated spirit, — clear spirit, — the staining fluid suitably 

 diluted with water, — absolute alcohol, and lastly, oil of cloves, 

 should be arranged on the table in the proper order, so that the 

 sections may be lifted from one to the other — after remaining a 

 few minutes in each. Finally, the section is taken on the lifting 

 instrument from the oil of cloves, allowed to rest for a few seconds 

 on some blotting-paper, then laid on the centre of a glass slide, 

 and covered with a thin glass circle, bearing a drop of the mounting 

 medium. Dammar varnish — or balsam softened with chloroform — 

 will be found the best for objects prepared as above described. 



Spibers : ^beir Structure anb Ibabite^ 



By William Horner. 



FIRST PAPER. — Plate 7. 



I PROPOSE in this paper, after saying a few preliminary words 

 on the class Arachnida, to take up more particularly one 

 of its main divisions — Araneidoe ; and to consider the 

 structure, economy, and habits of the animals which compose it, 

 illustrating these by reference to some of the more remarkable 

 British species. 



The Arachnida are a class of Annulosa, closely allied to 

 the Crustacea, and include Spiders, Scorpions, Mites, etc. The 

 body is divided into segments, or somites, and is furnished with 

 four pairs of legs. 



There are two divisions of the Arachnida :— (i) Trachearia^ in 



