PROCEEDINGS OF SOCIETIES. 297 



Further proof of the reasonableness of Captain Lang's explanation 

 was affurded by the fact that when the web is tightly stretched with- 

 out touching the glass the thread may be seen, with a y*^ object-glass, 

 running through the viscid beads, which appear as if transparent and 

 strung on a thread. This would not be the case in a single viscid line 

 running by molecular attraction into beads or drops. The conclusion, 

 therefore, seems inevitable that as it is only the sj^iral or concentric 

 lines which are strung with these beads, they must be furnished from 

 the secretion proceeding from the single inner pair of spinnerets ; 

 the glands differing so materially from those of the two outer pairs 

 which have so much more work to perform. 



QuEKETT Microscopical Club. 



Ordinary Meeting, October 23.— Dr. Matthews, F.E.M.S., Presi- 

 dent, in the chair. 



Mr. E. Packenham Williams read a paper " On Cutting Sections 

 of the Eyes of Insects, and on a New Instrmnent for that purpose." 

 The method of preparing the head for cutting was first described ; the 

 most successful plan being first to shake the insect gently in a phial 

 of benzine — then to soak it in alcohol 60° over proof for a time vary- 

 ing from four to forty-eight hours — this was considered to be the most 

 difficult part of the operation, some specimens becoming hard sooner 

 than others; and it was suggested that the best preparations might 

 possibly be made from insects just on the point of emergence from the 

 chrysalis. The head, after being hardened, was to be imbedded in a 

 mixture of butter of cocoa and bleached beeswax, with the addition 

 of a little new Canada balsam. This compound melted at about 120''. 

 The head was to be placed in the wax so that the cut should be at 

 right angles to the chord of the segment forming the outline of the 

 eye, the most satisfactory section being that in such a direction as to 

 show the structure of both eyes. The cutter was to be wetted with 

 sjjirit of turpentine, and one cut having been made, a little wax of a 

 lower melting point was applied to the cut surface, so that the next 

 section might be supported by a thin film of wax, and the cavities of 

 the head were also to be filled with wax so as to give more effectual 

 support. For the same purpose a piece of tissue paper laid on the 

 face of the section was often advantageous. The wax was to be re- 

 moved by warming gently in turpentine, and the specimen could then 

 be mounted in new balsam. 



The instrument used was then minutely described. This con- 

 sisted essentially of a rotating circular cutter, and a contrivance 

 similar to the slide-rest of a lathe, by means of which the thickness 

 and direction of the sections could be adjusted, and the object advanced 

 against the cutter while rotating. The cutter was extremely thin, 

 and moved with great accuracy in an exact plane. This was possible, 

 because it could be ground, polished, and sharpened on the pivots and 

 in the position which it would permanently occupy. The slide regu- 

 lating the thickness of the section could be adjusted to the -j- ^^^ ^ 

 of an inch, while that which advanced the object against the cutter 



