cross-subnet browsing

[John E Hein]

I have 2 subnets.  Subnet 1 has an NT WINS server.  Subnet 2 has a Samba
 server acting as domain master browser and local master browser
 for a workgroup.

If I view the network neighborhood from a Win 95 PC on Subnet 1
 (call it PC_A), I can see all the hosts in the workgroup on both subnets.

If I view the network neighborhood from a Win 95 PC on Subnet 2
 (call it PC_B), I cannot see PC_A.  I CAN 'map a network drive' on PC_B
 for a directory that has been shared by PC_A.

Both PCs are in the same workgroup (which happens to be the same
 workgroup as the Samba server).

What might be the reason(s) that I can map a network drive of
 a PC, but cannot see it in the network neighborhood?