Abstract: For diagnosing bodily functions of a patient by analyzing individual, samples several blood samples are taken from the patient automatically in sequence at predetermined time intervals, collected together separately from one another, retained until the completion of all the samples, and then analyzed. The blood samples are fed into a single collecting container one after another in time sequence with the aid of a control valve and are held separated from one another by the introduction of a separating medium between them or they are fed individually in sequence into separate containers. An anti-coagulant prevents the blood samples coagulating before analysis, and so the patient can wear the apparatus for taking the blood samples and can move about and behave normally throughout the sampling sequence.