  The paper reports analysis of momentum fractions carried by quarks and gluons
in models of Proton structure functions at small $x$. First, we analyze the
model proposed by Lastovicka based on self-similarity sometime back. We then
make a similar analysis for a second model based on the same notion which is
also free from singularity in $x$ : $0<x<1$. The predictions of both the models
are then compared with a recent QCD based Froissart bound compatible model of
proton structure function at small $x$, suggested by Block, Durand, Ha and
McKay. The results are then compared with the corresponding study in
perturbative and Lattice QCD.
