Royal Institutioti of Great Britain. idl 



the change of plumage. The ovarium was shrunk, purple, and 

 hard; the oviduct diseased, and the canal obliterated at the upper 

 part, immediately preceding its infundibuliform enlargement at the 

 bottom of the ovarium. Having opened a hen pheasant in her 

 natural plumage, for the sake of comparison, he found a similar 

 diseased state of the organs to exist ; thus proving that the disease 

 must exist some time before the corresponding change of feather 

 takes place. He observes, that it is no uncommon thing to find 

 among numerous broods of pheasants reared by hand, some females, 

 which, at the age of only four months, produce the brightest plu- 

 mage of the male; and in two instances of birds shot in a wild 

 state, the nest feathers had not been shed, proving them to have 

 been birds of the year. 



A partridge, having a v/hite bar across the breast, and the first 

 three primaries in each wing white, being opened, exhibited the 

 same sort of organic disease; and, from circumstances adduced, it 

 appears that this was also a bird of the year. 



But all variations in plumage are not traceable to this cause. In 

 most of the excepted instances, however, the individuals are dwarf 

 birds; and the author attributes their variety of plumage to defec- 

 tive secretion — the effect of weakness. 



When the sexual organs are artificially obliterated in the com- 

 mon fowl, so- soon as the operation is performed in the male bird 

 he ceases to crow, the comb and gills do not attain their full size' 

 the spurs remain short and blunt, and the feathers of the neck as- 

 sume an appearance intermediate between the hackled character of 

 the cock and the ordinary web of the hen. When the oviduct of 

 the female is obliterated, the ova cease to enlarge ; she makes an 

 imperfect attempt to crow ; the comb increases in size, and short 

 and blunt spurs make their appearance. I he plumage alters in 

 colour and in form, approaching to that of the cock, the bones of 

 the lower part of the back never acquiring the enlargement requisite 

 for giving a proper breadth to the pelvis. In short, the two sexes 

 approximate so nearly in character by this process, that it frequently 

 becomes difficult to determine the sex. 



Hen pheasants assume the plumage of the male at best but im- 

 perfectly, and it is probable that they do not live many years after 

 the change. 



It appears to be a general law, that where the sexes of animals 

 are indicated by external characters, these undergo a change, and 

 assume a neutral appearance, whenever original malformation, 

 subsequent disease, or artificial obliteration, has deprived the sexual 

 organs of their true influence. 



ROYAL INSTITUTION OF GREAT BHITAIN. 

 May 25.— On the different methods and principles of ship-build- 

 mg,with particular illustrations of those due to Sir Rob. Scppings, by 

 Mr. Holdsworth.— The different methods of building were explained 

 b^ very fine models and clear descriptions ; illustrations both histo- 

 rical and practical, being drawn from various nations : the peculiar 

 advantages of the late improvements were pointed out. 



K 2 Models 



