Russian type has thus been maintained from Novgorod to the Pacific, with but minor differentiations on the outskirts - and this notwithstanding the great variety of races with which the Russians have come into contact.
Discriminants.-The discriminant of a homogeneous polynomial in k variables is the resultant of the k polynomials formed by differentiations in regard to each of the variables.
That the oceanic blacks form one family there can be no doubt, and it is evidence of the immensely remote date at which their dispersion began that they have a multitude of languages often unintelligible except locally, and an extraordinary variety of insular customs: differentiations which must have needed centuries to be effected.
The young cell-wall is always tenuous and flexible, and may remain so throughout, but in many cases thickenings and structural differentiations, as well as the changes referred to above, alter the primary wall considerably.
When present, the branchiae are generally differentiations of parts of the appendages, most often the epipodites, as in the Phyllopoda.