2o6 THE MICROSCOPE. 



mica, as the mica is very thin and when mounted can instantly 

 be heated to an intense heat over an alcohol lamp. With 

 a pair of scissors cut small strips from the best part of the 

 diatom field of mica, moisten the mica on the other side and lay it 

 on the prepared slide near the center of the slip to be used, or if the 

 diatoms are to be mounted on a cover-glass, place the strip near it 

 and with a pen make a delicate dot of ink on the under side of the 

 slide to mark the place for placing the diatom. From the mica the 

 diatoms can be very easily picked, while from glass it is sometimes 

 almost impossible to pick them. Several strips of mica may be 

 placed side by side with different kinds of diatoms if desired. 



Those who desire to arrange diatoms will find the following 

 suggestions of value: Instead of putting the diatoms on a cover- 

 glass and the cover-glass on a metal strip, in order that organic mat- 

 ter may be burned away over a spirit lamp, put them with a pipette 

 on the end of a thin strip of mica and then burn them, avoiding the 

 great annoyance of having a cover-glass, diatoms and all, slide or 

 fly off. The mica being thin and a poor conductor of heat, the end 

 may be brought to a red heat almost instantly. Now place a glass 

 slip on the turn-table and make a dot or a small circle in the center 

 as a guide for placing the diatoms. Turn the marked side down 

 and with gelatine or other material size the spot over the dot or 

 circle; then with scissors cut from the film of mica a small piece 

 from the best part of the diatom field, moisten the other side and 

 lay it on the glass slide near the marked center. A crescent-shaped 

 piece may be cut if desired that may extend partially around the 

 marked spot. The mica being thin the focus of low powers need 

 not be changed while transferring the diatoms from the mica to the 

 slide, and one trial will demonstrate that it is much easier to pick 

 from mica than from glass; also that there is less danger of having 

 the mica fall from the slide while at work. Those who desire to 

 make the arrangement on a cover-glass can do so by placing a cover 

 over the marked center, sizing it and then transferring to the cover 

 instead of to the slide. 



Died, at his home in Boston, on November 17, 1883, Mr. .R. 

 B. Tolles. A full account of his valuable services to thescience of 

 microscopy, will be given in the January number of this journal. 



