the hid 12 may be formed in various manners fig1 7 depict a first embodiment of the lid 12 wherein a boss 26 extends upwardly from a top surface 27 of a top 28 of the lid 12 as best shown in fig3 and 4 a channel 30 extends from an opening 32 formed at an end of the boss 236 with the channel 30 coming into communication with a plurality of secondary channels 34 that extend through the top 28 and terminate at openings 36 formed in a lower surface 38 of the top 28 in a preferred embodiment latchable members 40 extend from the lower surface 38 which are formed to engage and latch onto the multiwell plate body 16 each of the latchable members 40 includes a deflectable downwardly extending arm 42 which terminates at an inwardly extending tab 44 with this configuration generally defining a l shape preferably the latchable members 40 are integrally formed with the lid 12 and formed of a resilient material preferably a thermoplastic a sufficient number of the latchable members 40 is provided to facilitate tight latching of the lid 12 onto the multiwell plate body 16 in a preferred arrangement each of the corners of the lid 12 is provided with one of the latchable members 40 to generate a perimetric holding force with reference to fig5 7 the method of preparing the multiwell plate assembly 10 is depicted therein as shown in fig5 in a first step a source of negative pressure such as a hose 46 is connected to the boss 26 and the lid 12 is positioned in proximity to a supply of the gasket members.