In 1668, Francesco Redi wanted to know if meat could spontaneously produce maggots as many people thought at the time. Redi believed that the maggots came from flies that lay eggs on the rotting meat. He placed one piece of meat in a jar and covered it with cloth. He left another piece of meat in a jar uncovered. After two weeks, he inspected the meat and found that the one in the covered jar did not have maggots, but the one open to the air did have maggots.

Explanation UR DAD LOL BISXH

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.