and Laboratory Methods. 



1780 



(Figs, o and 4), the microscope being without mirror, condenser or eyepiece. 

 With spherical, opaque eggs it is best to attach them by means of collodion to a 

 piece of glass. A concavity of lesser diameter than the egg is made on the glass 

 by means of a drill. The egg is placed on this in a watch glass of ether and 

 alcohol for a few minutes. The glass plate is then moved up against the 

 edge of the watch glass until the egg is out of the ether and alcohol. Sur- 

 plus fluid is blotted or drained off, and then by means of a slender wood or 

 glass rod a minute drop of thin collodion is allowed to run beneath the egg by 

 touching the glass at the point where it comes in contact with the specimen. 

 After a moment the glass plate and egg are immersed in either alcohol or 

 formalin. The collodion hardens almost instantly and holds the egg in place. 



The glass plate is now placed on the microscope stage in a dish of alcohol 

 or formalin and upon a back- 

 ground. For a light colored ^^"^^ 

 object, black, blue or purple 

 glass or black velvet affords 

 a sufficiently non-a c t i n i c 

 background. For a darker 

 colored object either white 

 glass or white cardboard may 

 be used. 



For a magnification of 15 

 diameters the most satis- 

 factory results have been ob- 

 tained with the Bausch & 

 Lomb-Zeiss 3-inch micro- 

 planar,* though very good 

 results may be had with the 

 much cheaper 70 mm. projec- 

 tion lens of Zeiss or the 80 

 mm. projection lens of Leitz. 

 Eyepieces are of course not 

 used with any of the lenses. 



The objective having been selected the camera length is adjusted according to 

 the magnification desired. A table should be constructed for the purpose for 

 each objective used. 



The object is illuminated by the arc light as already described. In order to 

 regulate the shadows a small cardboard reflector is made use of. This is attached 

 by sealing wax to the end of a lead wire which is supported from a brass or lead 

 disc on the microscope stage. By bending the wire the reflector may be brought 

 into any position (Fig. 4). 



Focusing is accomplished with low powers by means of the coarse adjust- 



* This lens as furnished by the makers has a diaphragm ring so large that it cannot be used 

 inside the tube of the Zeiss photomicrographic stand of the older pattern. Since the lens is of 

 too long focus to be used at the lower end of the tube of this microscope, the diaphragm ring 

 must be filed down. The lens may then be used inside the microscope tube ori the adapter fur- 

 nished by Zeiss for such lenses. 



Fig. 7. — Uiiio Sp. Photographed under water. B. & L. 

 Zeiss-Anastigmat Series Il-a (No. 3). Bellows length 

 32. .5 cm.; direct sunlight ; Seed's process plate ; exposure 

 15s. Bromo-hydrochinone developer, x 1. Surface re- 

 flection makes this a difficult object to photograph except 

 under water. 



