A HEN’S EGG 213 
yoke gradually swings round into the proper position. Any 
sudden turning of the yoke, however, might injure the 
developing chick ; this is guarded against by the balancers, 
which act as buffers and anchors, preventing concussion 
against the shell and securing a slow and gentle movement. 
The bird, as we have seen, is continually turning her eggs, 
with her feet and beak; hence the necessity of some 
arrangement which will prevent the contents from being 
injured. 
The object of turning the eggs in the nest is slightly to 
alter the position of the chick from time to time and so to 
prevent the contents of the shell from interfering with its 
natural growth. Eggs kept in incubators without being 
turned either fail to develop or produce delicate mis-shapen 
chicks. Parts of the bird come in contact with the shell- 
membrane or other objects and having lain in the same 
position for some time, either grow to the objects. or 
become mis-shapen; the germ develops into a weakly 
chick, which may be unable to break through the shell 
without serious injury. 
Notr.—A good deal of the work outlined in this chapter might 
be done out of doors, indeed it is best taken beyond the school walls. 
It has been placed after the chapters on birds so that the 
information collected whilst going through that part.of the course 
might be available. Taken here it affords a useful opportunity 
for revision, as well as for gathering together and focussing the 
knowledge already acquired. 
The methods of dealing with such a subject as a hen’s egg are 
so obvious as to require but little further amplification. The 
whole of the investigation should be made clear by requiring each 
step to be seen and understood by pupils before passing on. 
It is not desirable—indeed it is rather beyond the scope of 
primary school work to follow the development of the chick, so 
that all detailed mention of it has been omitted. 
