PROGRESSIVE POULTRY CULTURE 55 



The embryo, at this stage, 'shows some independent 

 movement when the egg is held still before the tester, 

 It appears to swim in a clear space. It is. in fact, sur- 

 rounded by a sac filled with thin, transparent fluid (the 

 amnion) which is imbedded in the yolk and helps to 

 prevent the embryo's too near approach to the shell, 

 during the first half of the period of incubation. 



At this time eggs from under the sitting hens should 

 be carefully compared with some from the incubator. 

 If the eggs from both machine and hens appear alike 

 in their development, it is safe to conclude that the ma- 

 chine is providing conditions of incubation that are 

 satisfactory. If decided differences in appearance are 

 noticed the same should be carefully studied. The eggs 

 under the influences of natural incubation may show, 

 before the tester, only slight increase in the size of the 

 air-cell, somewhat dull and indistinct outline of the 

 blood-vessels and slightly blurred appearance of the 

 embryo while the eggs from the incubator may show 

 bright scarlet veins having their edges sharply defined 

 and an embryo distinctly outlined, dark in color and 

 with an eye-spot decidedly black. Possibly the air-cell 

 has increased considerably in size. 



If any of these differences in appearance are ob- 

 served by the experimenter he may conclude that the 

 hens are doing better incubating than the machine. 

 Appearances as noted indicate that the fertile eggs under 

 the hens should successfully hatch into strong chicks. 



The artificial method, however, according to the in- 

 dications mentioned, has provided too high a temperature 

 at some time or times, too much air (excessive ventila- 

 tion) or too little moisture in the atmosphere of the 

 egg-chamber during the early days of incubation. The 

 heart action and blood circulation are too emphatic and 

 there may come reaction. 



If, furthermore, the bordering vein of the blasto- 

 derm shows through the shell of the egg, it is additional 

 and emphatic testimony to the injurious effects of one 

 or more of the unfavorable conditions just mentioned. 

 If the bordering vein appears as a bright red circle 



