74 American Quarterly Microscopical Journal. 



fine ruling. Perhaps there is nothing more wonderful as an instance 

 of fine mechanical work than the delicacy and accuracy with which fine 

 lines are now drawn upon glass. The delicate curves here described 

 are attracting considerable attention, and by some are considered supe- 

 rior to Nobert's plates as test objects, from the mere fact that the lines 

 are not parallel, but cross or gradually approach each other. The cuts 

 are apparently V shaped grooves, and, if desired, a " vertically waved 

 line " can doubtless be made. Although the lines are all practically in 

 the same plane, an alteration of focus is required to bring out the 

 transverse lines. 



On a New Micrometer.— George J. Burch. — This is illustrated by 

 a plate, but the principle can readily be grasped without a figure. 



About ten inches from the body of the microscope a scale, drawn on 

 ivory or card, is supported, level with the eye-piece. An arm reaching 

 from the eye-piece acts as this support. A Beale's neutral tint camera 

 lucida is placed above the eye-piece so as to throw an image of this 

 scale, properly illuminated, into the eye. At the same time, any object 

 upon the stage is seen through the camera. The object and scale 

 being thus seen together, measures can be at once read off. Other cam- 

 eras than Beale's can of course be substituted. Many advantages are 

 claimed for this instrument. It is certainly capable of many applica- 

 tions apart from measuring with the microscope, as, <'.^'-. the internal 

 diameter of the mouth of a bottle can be measured by simply using a 

 tube ten inches long in place of the microscope. 



On a Method of Mounting Whole Insect.s, without pre.ss- 

 URE, FOR THE BINOCULAR MICROSCOPE. — Staniforth Green. — The 

 smaller insects should be killed by placing them in turpentine. They 

 thus die usually with wings and legs outspread. After a few days soak- 

 ing in turpentine they are ready to mount in balsam. With horny 

 kinds turpentine cannot be so used, as these curl up in dying. Such 

 must be placed alive on glass, and while walking a cover glass placed 

 upon them, and strong alcohol then introduced to kill them in posi- 

 tion. Mount in balsam as usual. 



Moderate sized Diptera must be held by the wings and dipped in 

 turpentine, and allowed to remain in this for five minutes. Then hold 

 them by the wings, spread out the legs with needles on glass, replace 

 in turpentine for a few minutes, and then heat them in turpentine 

 until boiling begins. When heated enough tongues and ovipositors 

 will be found protruded. Place then in cold turpentine until ready 

 for mounting. 



Spiders are killed in alcohol, placed between pieces of glass, arranged 

 with needles, and soaked in turpentine. 



On Variation in Spongilla fluviatilis. — J. G. Waller. — This 

 is a thoroughly good article, and we want more such. It is a plain- 

 spoken protest against giving specific names to mere varieties. There 



