Sentence:  Scarcity of <WSD>paper</WSD> caused many Southerners to adopt the practice of cross writing , i. e. , after writing from left to right of the page in the usual manner , they gave the sheet a half turn and wrote from end to end across the lines previously written . 
Meaning of the word marked with <WSD> tags:  a material made of cellulose pulp derived mainly from wood or rags or certain grasses