REVIEW 311 
this extra oxygen, the pulmonary circulation becomes active, the 
embryonic circulation ceases, and the allantois shrivels up, since 
jts use is no longer needed. The chick now has room to move its 
head, ‘and it begins to break the shell by dealing blow after blow with 
its beak upon one spot on 
the inside until the shell 
is punctured (Fig. 150). 
This performance is re- 
peated, in a new place 
each time, until the shell is 
broken all around about 
one-third of the distance 
from the large end. All 
the chick now has to do ‘ Fie. 150.—Hatching time. One egg completely 
to get out from the shell is | pipped ready for the final effort of the chick; the 
46 forse ee parts of ee a resting after the effort. (Photo by 
the shell apart by pressing 
its feet against the small end and its head against the large one, 
which it throws off. It takes the chick some time to dry off and 
get the use of its legs, and usually from one to three hours elapse 
after hatching before it becomes very active. 
REVIEW. 
. Why need the fowl’s reproductive system be so complicated? 
The hen’s reproductive system is composed of what two parts? 
Where is the ovary located and what is its work? 
. Describe the appearance of the ovary and yolk sacs. 
. Describe the maturity of an ovum and its entrance into the oviduct. 
What is the oviduct? What are its uses? 
. Where is the egg fertilized? 
. Describe the changes in the egg during its passage through the oviduct. 
. Enumerate the parts of a completed egg, and give the use of each part. 
. Give the approximate composition of the whole egg, with and without 
the shell. 
11. Mention the types of malformed eggs, and give the cause of each. 
. Discuss the fertile and infertile egg. 
. Describe the development of the embryo which takes place before the egg 
is laid. 
. Describe the first day’s development during incubation. 
. Describe the appearance of the embryo when thirty-six hours old. 
. Describe the appearance of the embryo when seventy-two hours old. 
. Give subsequent development from third day to hatching time. 
. Describe the process of hatching. 
— 
SOMNAARwWIe 
ae 
wry 
Pilar tl <i ail nw’ 
ONO 
Reference.—Reproductive Organs of the Hen, by D. F. Laurie, South 
Australia Department of Agriculture Bulletin 72. 
