338 THE AMERICAN MONTHLY [Nov., 



that could be desired, but these cannot be supplied with 

 every laboratory microscope and neither can the stops 

 for the Maltwood finder be used in all cases. To attain 

 the object of marking preparations and at the same time 

 leaving the microscope and the prexjaration in as simple 

 a condition as though no special marks were used was 

 attained by Dr. May of Philadelphia, and later by 

 Winkel of Groettingen, by means of an objetive like appa- 

 ratus in which a diamond point might be made more or 

 less eccentric, depending on the circle desired, and then 

 by rotating the carrier of the diamond a slight scratch 

 was made on the cover enclosing the object. The diffi- 

 culty here is that the line must be so fine that it is diffi- 

 cult to find the circle in the first place and in the second 

 place homogeneous objectives cannot be used as the fluid 

 would obliterate the diamond line unless they were filled 

 with plumbago and protected in some way. 



To overcome these difficulties and mark the specimens 

 easily and so plainly that there was no trouble in finding 

 the right field, the writer for many years, made an ink 

 mark near the edge of the field with a fine peR, then 

 placed the slide on the turn table and made a delicate 

 circle of colored shellac or other cement around the 

 place indicated. This answered fairly well, but to be 

 able to have a marker on the nose-piece and whenever 



any object was found that 



showed a spec- I TllrN I ^^^ structure 



well seemed so ( ft) ) desirable that 



the device of VJliy May & Winkel 



was modified =^ by using a 



small brush. This brush was attached to a piece that 

 could be made eccentric, then this to another, rotating 

 on a central axis which was screwed into a piece with 

 Society Screw, which in turn could be attached to the 

 nose-piece. With this simple apparatus every object 

 showing a particular structure well can be marked in half 



