Germans aided only by the fraction of those living there previously, most of whom were not ethnically German. In order to meet the imaginary targets, Gauleiter Albert Forster, in charge of Reichsgau Danzig-West Prussia, had decided that the whole segments of Polish population are in fact ethnic German, whilst expelling others. This decision led to some two-thirds of the ethnic Polish population of the Gau being defined as "Germans" for the first time in their lives. German Nazis closed elementary schools where Polish was the language of instruction. Streets and cities were renamed (Łódź became Litzmannstadt, etc.). Tens of thousands of Polish enterprises, from large industrial firms to small shops, were seized from their owners. In October 1939, the Nazi propaganda stated Poles, Jews, and Gypsies were subhumans. Signs posted in front of those establishments warned: "Entrance forbidden for Poles, Jews, and dogs." The Nazi regime was less stringent in their treatment of the Kashubians in the Reichsgau Danzig-West Prussia. Everywhere, however, many thousands of people were forced to sign the Deutsche Volksliste, a racial documentation which the Nazis used to identify and give priority to people of German heritage in occupied countries. Crimes against children At least 200,000 children in occupied Poland were kidnapped by the Nazis to be subjected to forcible germanization (Ausländerkinder-Pflegestätte). These children were screened for "racially valuable traits" and sent to special homes to be Germanized. After racial tests, those deemed suitable, were then placed for adoption if the Germanization was effective, while children who failed the tests were mass murdered in medical experiments, concentration camps or sent to slave labor. After the war, many of the kidnapped children found by Allied forces had been utterly convinced that they were German. Children of forced workers were brutally mistreated in Nazi birthing centres for foreign workers, where thousands of them were murdered outright or through calculated neglect. Many of the mothers who were unable to return to work after giving birth were murdered. A camp for children and teenagers, Polen-Jugendverwahrlager der Sicherheitspolizei in Litzmannstadt, ran from 1943 to 1944 in Łódz, with a sub-camp for girls in Dzierżązna, Łódź Voivodeship. Cultural genocide As part of the Nazi plan to destroy Poland, the Germans engaged in cultural genocide in which they looted and then destroyed libraries, museums, scientific institutes and laboratories as well as national monuments and historic treasures. They closed down all universities, high schools, and