i86o 



The Cornell Reading-Courses 



In Fig. 72 are shown drawings of some eggs containing living germs on 

 the fourteenth day of incubation, and of other eggs in which the embryo is 

 dead. By comparing the air cells as shown in Figs. 70 and 71 with those 

 shown in Fig. 72, it will be seen that the air cell increases in size during the 

 first two weeks of incubation. This increase continues until about the 



H S ■ 6 9^H„ 



Fig. 70. — Eggs as they appear when held before tester after seven days of incubation, 

 compared with fresh egg: i, Fresh egg; 2, infertile egg; j, weak germ; 4, strong germ as 

 most commonly found; 5, strong germ very near air cell; 6, germ not visible 



nineteenth day, the size of the cell varying somewhat with the individual 

 eggs in the same incubator or under the same hen. The air cells in eggs un- 

 der the hen are usually smaller than those in eggs artificially incubated. 

 Eggs incubated in moisture incubators generally have smaller air cells than 

 those incubated in non-moisture incubators. The air cell is found or- 



