Slide tray and slide holder

Claim 1

IN A SLIDE TRAY AND SLIDE HOLDERS, A SLIDE TRAY OPEN AT ONE SIDE AND HAVING A PLURALITY OF GENERALLY V-SHAPED PARALLEL SEPTUMS DEFINING GUIDEWAYS FOR RECEIVING SLIDE HOLDERS, AND A PLURALITY OF SLIDE HOLDERS HAVING FRONT AND REAR SIDES, EACH OF THE GUIDEWAYS HAVING A BLOCKING PORTION ASYMMETRICALLY POSITIONED THEREIN, EACH OF THE SLIDE HOLDERS HAVING AN ASYMMETRICALLY POSITIONED RELIEVED PORTION PROVIDING CLEARANCE TO PERMIT INSERTION OF THE SLIDE HOLDER INTO EACH GUIDEWAY IN ONLY ONE POSITION RELATIVE TO THE TRAY, THE UPPER PORTION OF EACH GUIDEWAY AND THE UPPER PORTION OF EACH SLIDE HOLDER BEING COMPLEMENTARY IN SHAPE, THE LOWER PORTION OF EACH GUIDEWAY AND THE LOWER PORTION OF EACH SLIDE HOLDER BEING ASYMMETRICAL IN TRANSVERSE CROSS-SECTION AND BEING COMPLEMENTARY IN SHAPE RELATIVE TO EACH OTHER, THE SHAPE OF THE UPPER PORTION OF EACH SLIDE HOLDER BEING SUCH RELATIVE TO THE LOWER PORTION OF EACH GUIDEWAY AS TO PREVENT INSERTION OF THE SLIDE HOLDER INTO THE GUIDEWAY WHEN THE SLIDE HOLDER IS IN AN INVERTED POSITION.