Petri dish provided with means forming evidence of use

A Petri dish comprising:

• a receptacle and of an additional lid, which both have a revolution shape and which are each delimited by a bottom wall and at least one peripheral wall;
• a wall of said receptacle or respectively of said lid bearing at least two angularly equidistant fingers generally parallel to said bottom wall, which radially protrude towards said wall of said lid or respectively of said receptacle;
• while said wall without any fingers bears a same number of locks provided with a cam path able to receive said fingers;
• this receptacle and this lid may selectively occupy either one of successive different positions indicated below:
• (a) a first position, a so-called “non-locked beforehand” position, in which said fingers are not received in said locks;
• (b) at least one “intermediate position” selected from:
• (i) a “non-ventilated locked” position, in which said fingers are received in said locks in which said receptacle is in intimate contact with said lid, so that an internal space which they delimit is isolated from an outside medium, and
• (ii) a “locked and ventilated” position in which said fingers are received in said locks and in which the receptacle is not in intimate contact with said lid, so that said internal space which they delimit is not isolated from said outside medium;
• (c) a “final position”, a so-called “read out” position, in which said fingers are released from said locks and allow lifting of said lid;
• passing from one position to a next position being accomplished at least by a relative rotation of relatively to said receptacle, in a same direction;
• wherein said locks bear at least one blocking member which blocks said fingers in an “intermediate position”, which opposes the return to the “first position”, while allowing passing to said next position, said blocking member being an anti-return ratchet.