1858 



The Cornell Reading-Courses 



with an egg-testing device will answer the purpose, provided it gives a 



good flame; or a Rochester burner may be used without the testing device 



by placing a sheet of asbestos between the testing room and the lamp 



chimney. In case a testing device is used, the opening in it should be 



placed against the small hole in the rear wall of the testing room. By 



placing casters on the four legs of the testing room it may be moved 



from one incubator to another, thus avoiding the extra labor of carrying 



the eggs to and from the place where they are tested. This arrangement 



will prove a decided advantage in connection with incubators of large 



capacity; also, testing may be done 



very accurately during the daytime. 



The construction of this testing room 



is shown in Figs. 67 and 68.^ 



If the operator prefers to do the 



testing at night, a common testing 



device and a house lamp are sufficient 



for the purpose. On bright, sun- 



)2 shiny days testing may be done 



^ accurately without a testing room by 



'■3 using a frame that fits tightly against 



a window facing toward the sun. This 



frame should be covered with heavy 



black cloth or paper, in which is cut 



a round or oval opening about the 



size of an egg. This arrangement is 



illustrated in Fig. 69. 



During the winter it is advisable to 



cover the trays of eggs while they 

 Fig. 68. — Sideview of testine room, wall , • . . j o^i • • j. 



cutaway,s}wwing:i, Testing device; are bcmg tested. This IS not ncces- 



2, lamp; 3, egg tray; 4, tray for in- sary in a warm roofn unless the eggs 



fertile and dead germ eg? - r ,1 • 1 , r 



■' if.* j^j-g Q^^ Qj: ^j^g mcubator for some 



time. In case the first test is made on the seventh day of incubation, 

 the live germ, if it is strong, will show distinctly the blood vessels 

 branching in various directions. The germ should be centrally located in 

 this network of blood vessels, and it is usually found near the air cell, 

 provided the egg is held with the large end up. A live embryo is easily 

 moved by turning the egg about. Occasionally the germ will be hardly 

 visible, but its presence is readily detected by a darker appearance of 

 the egg contents than is shown by an infertile egg. If for any reason 

 the person doing the testing is in doubt as to whether a germ is alive 

 or dead, it is well to mark the egg and test it later; this practice will 



' Mr. Robert Herman of Lakewood, New Jersey, designed a room very similar to the one shown here. 



