Before brands like Schaffer and Esterbrook came out with the plastic cylinder ink cartirdges you used a bottle of ink and dipped the nib of the pen into the ink. There was a little lever farther back along the body of the pen. You would lift that up to suck in into the pen bladder. Man permanent ink was messy in the 40' and 50's. Even the plastic ink cartridges leaked at time. It was similar to using a syringe and sucking it into the glass tube part.