Detention and seizure of goods released upon payment of prescribed penalties or furnishing security; sale if unpaid. Section 129 permits detention or seizure of goods and conveyances transported or stored in transit in contravention of the Act; release follows on payment of prescribed penalties or on furnishing equivalent security. Penalties differ if the owner comes forward (penalty equal to two hundred per cent of tax or specified amount for exempt goods) or does not come forward (penalty equal to fifty per cent of value or two hundred per cent of tax, or specified amount for exempt goods). The proper officer must issue a notice within seven days and pass an order within seven days of that notice; opportunity to be heard is required and unpaid penalties may be recovered by sale or disposal, with special rules for perishables.