452 
KUDIMENTAKY OKGANS. 
Chap. XIII. 
nascent breathing organ or lung. Other similar in¬ 
stances could be given. 
Organs, however little developed, if of use, should not 
be called rudimentary; they cannot properly be said 
to be in an atrophied condition; they may be called 
nascent, and may hereafter be developed to any extent 
by natural selection. Eudimentary organs, on the other 
hand, are essentially useless, as teeth which never cut 
through the gums; in a still less developed condition, 
they would be of still less use. They cannot, therefore, 
under their present condition, have been formed by 
natural selection, which acts solely by the preservation 
of useful modifications; they have been retained, as 
we shall see, by inheritance, and relate to a former 
condition of their possessor. It is difficult to know 
what are nascent organs; looking to the future, w^e 
cannot of course tell how any part will be developed, 
and whether it is now nascent; looking to the past, 
creatures with an organ in a nascent condition will 
generally have been supplanted and exterminated 
by their successors with the organ in a more perfect 
and developed condition. The wing of the penguin is 
of high service, and acts as a fin; it may, therefore, 
represent the nascent state of the wings of birds ; not 
that I believe this to be the case, it is more probably a 
reduced organ, modified for a new function: the wing 
of the Apteryx is useless, and is truly rudimentary. 
The mammary glands of the Ornithorhynchus may, per¬ 
haps, be considered, in comparison with the udder of a 
cow, as in a nascent state. The ovigerous frena of cer¬ 
tain cirripedes, which are only slightly developed and 
which have ceased to give attachment to the ova, are 
nascent branchiae. 
Eudimentary organs in the individuals of the same 
species are very liable to vary in degree of development 
