and Laboratory Methods. 24(31 



The Technique of Biological Projection and Anesthesia of 



Animals. 



COPYKIC.HTEI). 



XVI. DIFFERENT TYPES OF CELLS IN WHICH LIVE ANIMALS AND PLANTS 



ARE MOUNTED. 



In considering the question of cells in which to mount live organisms for 

 projection, three conditions which are essential to the greatest success should be 

 kept in mind. First, the live organisms will need sufficient water or air, accord- 

 ing as they are aquatic or airial, to sustain life during the experiment ; second, 

 the organism should be confined within reasonable limits relative to its size, 

 especially as regards the depth of the cell in the line of the optical axis of the 

 microscope, so that the specimen may be easily kept in focus; and, third, the 

 cell should be easily adjustable and movable on the stage of the projection 

 microscope. 



The cells shown in the accompanying engraving, Fig. 9, include nearly all the 

 available shapes of glass, or glass with metal or rubber, cells now offered in the 

 American and European markets and, in addition, some designed and made by 

 the author to meet special requirements. All of the cells have polished surfaces 

 in the parts which are in front of or behind the mounted organism in order that 

 the maximum amount of light and the best possible definition may be obtained 

 in the projected picture on the screen. Cells with rough or ground glass bottom 

 are not at all satisfactory in projection work. 



In Fig. 9, the cells numbered 1 to 13, also 15, 21, and 22, have loose covers 

 which are placed over the specimen after it is put into the cell ; while 14 and 16 

 to 20 are open at the top for the reception of the specimen, the front and back 

 being cemented on with water-tight joints. 



The cell numbered 1 is a polished plate glass microscopical slide 3 in. by 1 in. 

 for use in mounting amtebae, bacteria, infusoria, and other microscopic organisms 

 which are shown by the use of objectives of high power and correspondingly 

 short working distance ; 2 is a hollow-ground or culture slide, 3x1 in., with an 

 elliptical concavity ; 3 is similar to 2, but has a circular concavity (B. & L. Opt. 

 Co. Cat. No. 1306) ; 4 is a culture slide having a slightly concave center which 

 is surrounded by a deep groove ; 5 has an elliptical concavity about one and 

 one-fourth inches long, seven-sixteenths wide and one-eighth inch deep in the 

 center ; 6 has a similar but wider and shallower concavity in a plate of glass 

 which is cemented on a glass slide ; 7 is an embryo glass having a concavity one 

 and an eighth inches in diameter in a plate about four by one and one-half 

 inches ; 8 is an ordinary embryo glass one and an eighth inches square cemented 

 to a glass slide ; 9 is an embryo glass with only the bottom and the concavity 

 polished ; 10 is a form of life box simpler than B, &. L. Opt. Co.'s No. 1830 ;, 

 11 is a glass cell about four inches square and three-eighths inch deep ; 12 is a 

 small size, one and three-fourths inches square, of the same form as 11, and other 

 sizes are in the market ; 13 is an embryo glass two inches square ; 14 is a life cage 



