Between 1946 and 1949, a number of kanji were simplified.  As a result, when you read texts from before this time, it is common to encounter characters in their old form (旧字体).  The link below takes you to a chart that shows the characters that were changed, in both their old and new forms.

http://www.benricho.org/moji_conv/14_shin_kyu_kanji.html