1894 THE MICROSCOPE. 77 



eosin run over the specimen as prepared above until the ob- 

 ject is flooded. Let it soak from half an hour to an hour. 

 Then with forceps remove to a clean glass slip ; then float in 

 alcohol ; when the alcohol evaporates float in turpentine and 

 under a dissecting microscope see that the stained film is nicely 

 spread out. Then mount in balsam. You will have a slide 

 worth seeing and one that is not common. 



Etching Labels on Slides. — This may be easily accom- 

 plished and will produce better permanent labels than can be 

 written with a diamond. Coat a clean slide with bees wax b}^ 

 heating in the flame of a spirit lamp and spreading the film of 

 wax evenly. Trace the design wdth a needle through the glass, 

 in a little shallow lead dish one half inch deep and four inches 

 long and three inches w4de, place a teaspoonful of powdered 

 fluor spar and one half ounce of strong sulphuric acid. Across 

 the top place the slide or several slides, wax side down. Smear 

 the opposite side with vasiline and let it remain over night. In 

 the morning remove the wax with turpentine or chloroform and 

 the label will be permantly etched. Care must be taken while 

 performing the experiment as the vapor of hydrofluoric acid 

 generated is in the highest degree corrosive and its action upon 

 the human system is highly deleterious. The same result can 

 also be obtained in the course of a few minutes by a gentle ap- 

 plication of heat to the cup containing the mixture. 



To Obtain and Mount an Embryo Chick. — Take eggs 

 that have been partially incubated. By taking eggs which 

 have been set for difl'erent lengths the progress of incubation 

 may be watched and studied. To see the embryo, crack the 

 shell upon the side over an area as large as a half dollar ; then 

 pick away the pieces of the shell piecemeal without disturbing 

 the tough membrane just within. The latter must be carefully 

 torn away with forceps and the embryo will be found upon the 

 upper surface of the yolk with its axis at right angles to that 

 of the egg, with its head away from the observer, if the smaller 

 end of the egg be toward the right. 



With sharp scissors the vitalline (yolk) membrane is pierced 

 and a circle cut about the embyro just about the limiting vein 

 of the vascular area. On immersing the egg in a 75 per cent 

 salt solution at about 99° Fahrenheit, the blastoderm will 

 float and may be slipped upon the slide and with a pipette 



