700 RECORD OF CURRENT RESEARCHES RELATING TO 



tlie exact j)oiut wlien light can be passed tbrougli it, but before many 

 of the most interesting features are destroyed by over-cutting. 



Simple Mechanical Finger.* — The devices hitherto employed as 

 " Mechanical Fingers " depend, Mr. M. A. Veeder writes, upon the 

 lengthening of the part which supports the substage apparatus by means 

 of a tube specially fitted for the purpose, or by means of the para- 

 boloid, so that by a rack movement the slide may be lifted free from 

 the stage into contact with a hair or fine wire, which is held by the 

 stage forceps or by some contrivance designed especially for the 

 purpose. Contact having thus been established, the slide may be 

 lowered, leaving the object adhering to the hair, or by moving the 

 sliding stage the object may be pushed in any direction desired. 

 There is, however, another plan, which he finds to be simpler, and 

 even more effective in certain respects. With many Microscopes a 

 condensing lens is supplied, which is fitted to the limb of the instru- 

 ment by a ball-and-socket joint and sliding stem-rod. Unscrew this 

 lens and put in its place a piece of cork through which a needle 

 passes at a right angle to the stem. It is well to have two or three 

 pieces of cork fitted with needles having difi'erent points ; one, for 

 instance, may have a human hair projecting slightly beyond its point, 

 the hair being kept in place by winding with fine thread and coating 

 with gum ; another may have a flat point, made by breaking off and 

 grinding the fractured end ; other forms will suggest themselves 

 as experience may determine. The ball-and-socket joint should be 

 clamped or wedged, so as to move quite stifiiy. Bring the point of 

 the needle into view under the objective, and it may be made to touch 

 the slide, or be lifted away from it by simply turning the stem-rod. 

 Objects which are seen to adhere to the needle are lifted at once, and 

 another slide, slightly moistened by breathing on it, may be sub- 

 stituted for the one on the stage, to which the objects may be made to 

 adhere at any desired point by turning the stem-rod as before. By 

 moving the mechanical stage while the point of the needle is in 

 contact with the slide, objects may be pushed wherever desired on 

 the slide. In this case it is a decided advantage that both needle and 

 object remain within view however the stage is moved. Thus dirt 

 may be scraped away with the greatest ease. 



It is evident that such a contrivance, consisting essentially of a 

 ball-and-socket joint, and a sliding stem with a button attached to the 

 latter, so that it may be readily turned, might be fitted to the stand of 

 an ordinary bull's-eye condenser, and thus become available for use 

 with any microscope-stand. 



Slides from the Naples Zoological Station. — At the June meet- 

 ing of the Society some slides were exhibited (for the most part 

 illustrating the early stages of Invertebrates t), sent by the Zoological 

 Station at Naples through Mr. A. W. Waters. Microscopists will be 

 glad to hear that the Station have commenced a department under the 

 management of Mr. Fritz Meyer for the preparation of microscopical 

 objects on a large scale, a list of which they intend shortly to issue. 



* 'Am. M. Micr. Jouru.,' i. (1880) p. 88. t See Uat, iwst, p. 736. 



