GO 
VARIETIES. 
The mere number of individuals affected should not liowever lessen 
tlie interest and scientific value of the differences exhibited, as there 
must always of necessity be a full and sufficient predisposing cause 
which it should be our aim to discover. 
The internal organs of the animal are also ecpially subject to 
modification, and it is cpiite conceivable that anatomical differences 
might arise which would liave an important bearing on the origin of 
specific differences, a modification of the sexual system might debar 
or restrict intercourse with individuals of the species not similarly 
affected, and thus pave the way to further and permanent modi- 
fication. This aspect of the subject which has been termed Entergo- 
genesis, has not received much attention up to the present time, so 
that it is not at all certain, whether the internal change may not 
often be the prior one, in the evolution of new and distinct species, 
as Eimer from his observations on colouring considers that species 
mainly originate from variation due to constitutional causes. 
From whatever causes induced these modified and modifying forms 
are of the highest interest and importance, as exhibiting in actual 
progress the processes of differentiation which may ultimately lead 
to the evolution of distinct species, it is therefore very desirable that 
well-marked variations exemplifying the various lines of divergence 
should be designated by a distinct and preferably conventional 
varietal name. The adoption of this practice will undoubtedly 
facilitate their study, though it is seldom desirable to attach special 
and distinctive names to the intermediate forms connecting the 
extreme varieties with each other or wdth the parent form. These 
intermediate as well as the complex forms might where and when 
desirable be distinguished by a judicious though temporary combina- 
tion of names already applied, thus if it were wished to mention 
from any cause a specimen exhibiting a colour-variation in combina- 
tion with another peculiarity, its character could be concisely indicated 
by combining the names of its chief modifications; a sinistral Lhmvva 
iwmjra if also an albino would be alluded to as sinistrursnin- 
at/idldam, and so on in other cases without however listing the names. 
The term Sub-variety or Mutation is used when referring to the 
slighter modifications either of the typical shell or of the varieties, 
they are really the intermediate forms which connect and blend 
together the well-marked varieties with each other and with the 
