Third.—­That at present the internal organs are not accessible to examination by the X rays for two reasons:  First, because many of them are enclosed in more or less complete bony cases, which cut off the access of the rays; and, second, because even where not so enclosed, the thickness of the body, even though it consists only of soft parts, is such that the rays have not sufficient power of penetration to give us any information.

Fourth.—­Even if the rays can be made to permeate the thicker parts of the body, it is doubtful whether tumors, such as cancers, sarcoma, fatty tumors, etc., which are as permeable to the rays as the normal soft parts, can be diagnosticated.  Bony tumors, however, can be readily diagnosticated; and possibly fibrous tumors, by reason of their density, may cast shadows.

Fifth.—­That stones in the kidney, bladder, and gall bladder cannot be diagnosticated, either (1) because they are embedded in such parts of the body as are too thick to be permeable by the rays, or (2) are surrounded by the bones of the pelvis, or (3) are, in the case of gall stones, themselves permeable to the Roentgen rays.

Sixth.—­That with the improvements which will soon be made in our methods, and with a better knowledge of the nature of the rays, and greater ability to make them more effective, we shall be able to overcome many of the obstacles just stated, and that the method will then probably prove to be much more widely useful than at present.

[Illustration:  FIGURE 11.—­SKIAGRAPH OF A HUMAN WRIST WHICH HAD BEEN DISLOCATED.

From a photograph taken by Mr. Herbert B. Shallenberger, Rochester, Pennsylvania, and reproduced by his permission.  This is a particularly interesting picture, because it not only shows the bones with unusual clearness, but also shows that the ulna (the small bone of the forearm) has been broken; a small projection at its lower end, which ought to appear, being absent from the bone as shown in the picture.]