likewise preferably arranged in order for it to be possible to specifically counteract foam development as occurs in many biological reactions the vessel 10 comprises an additional supply line for antifoaming agents afas called afa supply line 24 here for short the afa supply line is connected to a metering pump 26 which is able to pump antifoaming agents 28 from a storage vessel into the vessel 10 via the afa supply line 24 in the embodiment shown the afa storage vessel 30 is charged via its own supply line 32 having a sterile filter 34 a particular foam sensor 36 is provided for control of the metering pump 26 the foam sensor 36 comprises disposable elements which are connected securely to the disposable vessel 10 and together therewith can be sterilized and disposed of after use at the same time the foam sensor 36 comprises reusable elements which in the preferred embodiment do not require any sterilization since at no point do they come into contact with the interior of the vessel 10 securely connected to the wall of the vessel 10 is a window 38 which is at least transparent to visible and ultraviolet light window material which can be used includes both plastics such as for example pc pet pmaa etc and glasses for example float glass quartz sapphire etc in the embodiment shown the window 38 is connected to a plastics frame 40 in a secure and gas and liquid tight manner and the plastics frame 40 is connected more particularly welded or adhesively bonded to the wall of the vessel 10 in a secure and gas and liquid tight manner above the window the frame 40 has a collection.