Sentence:  You will be able to see radiographs, or <WSD>scotographs</WSD>, — referring to darkness and shadow ; you will see that shadowgraphs indicate to you any deformity of the roots of the teeth, or any teeth that have not come into position in the arch, or any osseous deformity which may take place in the jaw ... 
Meaning of the word marked with <WSD> tags:  An impression made on a photographic plate by a radioactive substance without the intervention of any opaque object other than the screen of the plate.