The most common defect in negatives, and one which it is easy to avoid, is the small transparent spots which appear on the negative after developing and fixing. These spots are called pinholes, and are caused by small specks of dust which cling to the film, and which do not wash off when the developer is turned over the plate. When a print is made from a negative in which there are pinholes, small black spots appear in the finished print wherever there were pinholes in the film. These holes can be filled up by retouching, but they may be avoided altogether, and prevention is much better than cure. After the sensitive plate is in the holder, dust it over carefully with a small wad of surgeon's cotton before putting in the slide. If plates remain in the holder some time before they are used, it is a wise plan to dust them again before they are put into the developer. Pinholes are sometimes caused by using old developer which has not been filtered, and the tiny specks which are in the solution settle on the plate during development. Always filter developer after once using, and it saves time if it is filtered at once when through developing. Larger spots with sharp dark edges are caused by air-bubbles forming on the plate when the developer is poured over it. If the tray is slanted a little when the solution is turned on the plate, air-bubbles are seldom formed. A piece of clean surgeon's cotton passed quickly over the plate will break the bubbles. Where there are large irregular spots on the plate which are not fully developed, it shows that the developer did not cover all the plate immediately, and therefore acted longer on one part than on the other. There is no remedy for this; but such markings can be prevented by pouring the developer quickly over the plate and rocking the tray for a few seconds. If the negative, after fixing, is covered with fine markings, the print looking as if the negative from which it was made was crackled, it shows that the tray was not rocked sufficiently during the process of development. The tray should be gently rocked in all directions, so that fresh developer is constantly passing over the sensitive film. (Not long ago one of the members of the club sent two prints to the editor, one of which was covered with fine markings. The letter stated that the negatives were made and developed one after the other; and while the first was all right, the second had the crackled appearance. An explanation of the cause was asked and received.)