MOULTINtt. 25 



yellowish-white colour, varying much in size 

 at different seasons ; they communicate by 

 short tubes uniting and ending in the vent. 

 In the hen, the yolk-bags are enclosed in a 

 single ovary, and pass out by a wide passage 

 erminating on the left side of the vent. 



We have stated enough for general pur- 

 poses ; it only remains to add a few words 

 on that particular process which occurs pe- 

 riodically to birds, and which appears con- 

 fined to no latitude, for it has been observed 

 among fowls from Iceland to the equator. 

 It is usually known under the name of moult- 

 ing, and implies the shedding of the old 

 feathers and the acquisition of new ones. 

 During the summer, the feathers of birds are 

 exposed to many accidents : many fall off 

 spontaneously, some are torn off in their 

 quarrels, others are broken or damaged, 

 and in many species they are plucked off 

 to line their nests. In this state, when au- 

 tumn approaches, they become feeble, mel- 

 ancholy, and languishing; their feathers 

 bristle up, and they are constantly engaged 

 in plucking out those which have a tendency 

 C 



