Between 1942 and 1944 millions of prisoners were subjected to forced labor in concentration camps throughout the Third Reich, all the while being the victims of a systematic and "scientific" extermination policy. Though the policy was directed mainly against Jews, it was implemented against other "inferior races" as well. The prisoners, stripped of all rights, experienced constant humiliation, uncertain survival and terror. The harsh living condition, characterized by crowding, absent sanitation and poor personal hygiene led to considerable morbidity, mainly due to injuries, infectious diseases and famine, and to high mortality rates. Medical care in the camps was the responsibility of the S.S. Each camp had a chief S.S. physician accompanied by a number of assistants and orderlies. There was also a parallel system of "prisoner-physicians." There was a chief prisoner-physician in every camp, and each block was assigned a "block doctor" who was responsible for sanitation, the removal of corpses, setting up the sick- call and authorizing sick leave. Work teams were accompanied by "mobile doctors" (Streckenpfleger), who dispensed first aid for work injuries. Prisoner-physicians were also charged with disinfecting the blocks and maintaining hygienic conditions in the camp. Every camp had one or more blocks, called "Reviers", that were used for treatment and hospitalization. In the larger camps a number of blocks were designated to function as a sort of hospital (Krankenbau). At times one camp out of a group of camps would be set aside as quarantine, primarily for patients with infectious diseases. Officially, the "Revier" was the responsibility of an S.S. physicians', assisted by a chief prisoner-physician, his assistants and, at times, nurses. But in actuality the Reviers were managed by prisoners (Capos) who did not have medical training but were authorized to make decisions in medical matters such as operations and, on occasion, even performed them. The Reviers suffered from shortage of everything: beds, manpower, diagnostic and therapeutic means, sterile supplies and drugs for anaesthesia. Crowding was the rule, and each cot was occupied simultaneously by several patients regardless of their condition or the nature of their disease. Life-saving procedures could not be performed and surgery, if done, was usually without anaesthesia. Mortality was high, and the Revier was commonly perceived by the prisoners as a place of death, not of healing. Occasionally there were visits, or inspections, by the S.S. physicians. The main purpose of those visits was "selection". Patients with no chance of recovery were sent to their death and the others were returned to work in spite of their condition. The prisoner-physicians made every effort to prevent this "selection" in various ways. They were often punished or even executed for their efforts.