The discovery of the cellular membrane was made by Carl Naegeli and C. Cramer in 1855. Their discovery provided important insight into many unanswered questions within the field of biology.
Carl Naegeli Wilhelm and C. Cramer proposed the first membrane as a means to explain what allowed cells to transfer materials back and forth the way they did. Despite the microscope being in existence since the 1600s, all that scientists could see up until this time was the cell wall itself, not the membrane underneath. As microscopes advanced and theories were formed, a picture of a cell membrane slowly emerged in the scientific community.