there are disclosed a shuttle apparatus and method for catching a test element ejected from an incubator , for carrying it to a station outside the incubator , e . g ., a wash station , and for returning it to a loading station . preferably , the apparatus comprises a simplified catcher plate and means for moving the plate in an arcuate path around a portion of the circumference of the incubator . the plate cooperates with stop means disposed above said arcuate path , to capture a washed element upon reloading , so that the washed element can be reloaded by returning it to the original path used to load elements into the incubator in the first instance .