Educational Ministries, Inc. 1998</ref> They were first observed by Anton van Leeuwenhoek in the 17th century, but he did not make the connection to disease. That had to wait for Pasteur's [[germ theory of disease]] 200 years later. | Educational Ministries, Inc. 1998</ref> They were first observed by Anton van Leeuwenhoek in the 17th century, but he did not make the connection to disease. That had to wait for Pasteur's [[germ theory of disease]] 200 years later. |