  We give a model where there is a ccc Souslin forcing which does not satisfy
the Knaster condition. Next, we present a model where there is a sigma-linked
not sigma-centered Souslin forcing such that all its small subsets are
sigma-centered but Martin Axiom fails for this order. Furthermore, we construct
a totally nonhomogeneous Souslin forcing and we build a Souslin forcing which
is proper but not ccc that does not contain a perfect set of mutually
incompatible conditions. Finally we show that ccc Sigma^1_2-notions of forcing
may not be indestructible ccc.
