Blood blood clotting in a transparent container. When blood is drawn in a glass container and left undisturbed for about an hour, four different layers can be seen. A dark clot forms at the bottom (the "black bile"). Above the clot is a layer of red blood cells (the "blood"). Above this is a whitish layer of white blood cells (the "phlegm"). The top layer is clear yellow serum (the "yellow bile"). The ABO blood group system was discovered in the year 1900 by Karl Landsteiner. Jan Janský is credited with the first classification of blood into the four types (A,
Blood, toil, tears, and sweat Blood, toil, tears, and sweat The phrase "blood, toil, tears and sweat" became famous in a speech given by Winston Churchill to the House of Commons of the Parliament of the United Kingdom on 13 May 1940. This was Churchill's first speech on 13 May 1940 to the House of Commons after having been offered the King's commission the previous Friday, to become Prime Minister of the United Kingdom in the first year of World War II. Churchill had replaced Neville Chamberlain on 10 May, and in this speech he asked the House to declare its confidence in his Government.