INCUBATION 95 



The Best Sitter. Cochin, Orpington, Plymouth Rock, 

 Rhode Island Red, and Wyandotte hens are the best 

 sitters. The quiet hen that will sit contented on the nest 

 until her work is finished and will then care for her 

 chicks properly is the kind to be depended on both for 

 raising utility fowls and fowls for exhibition. 



The most unsatisfactory hen for hatching is the nervous 

 hen that fusses and fights all who move about her; that 

 will spring quickly from the nest when any one ap- 

 proaches her, thus breaking her eggs and disturbing 

 those left in the nest. A good motherly hen that will 

 rear two broods in one season is the kind to be de- 

 pended on. 



Testing Fertility of Eggs. After eggs have been incu- 

 bated for some time, it is usually desirable that they 

 be examined for fertility. This examination may be 

 best made during the seventh day of incubation. The 

 work of testing the eggs can be done in daylight. To 

 do the work well, however, requires that it be done 

 after dark or in a darkened room. An appliance called 

 an egg tester is used for this purpose. 



Many kinds of egg testers are offered for sale. An 

 "excellent one is the kind that has a bull's-eye lens like 

 those used for bicycle lamps. A tester of this kind is 

 shown in operation in Fig. 3. The tester is placed over 

 the flame of any kerosene oil lamp, in a room that is 

 dark. The eggs should be placed against the opening 

 so that the light may shine through the egg; both live 

 and dead germs may then be clearly seen. 



Development of the Embryo. To one well trained in 

 the testing of eggs, the first material change will be 

 visible in about 48 hr. after incubation begins. The head 

 and the lines of the body can be seen by the trained 

 observer. The stages of development of the embryo are 

 shown in Fig. 4. To become expert in the testing of 

 eggs, one should compare the successive steps in the 

 development with the day on which it should occur as 

 recorded in this chart, which includes all the phenomena 

 from the first to the twenty-first day. 



