Word mail merge with Excel data

I've got a mail merge document set up in Word 2010. The data I'm using is Excel 2010. I've got some fields at the end of the data that have a lot of text in one cell (more than 255 characters).

Data at the beginning of the file is coming through just fine, but records that appear later do not -- they are cut off mid sentence.

I did find out that Word trea开发者_开发知识库ts records after a certain point as 'Text'. My question is:

How can I force Word 2010 to treat long fields (from Excel 2010) as 'Memo' and NOT 'Text'?

If I need to set up the MergeFields differently, I can. If I need to format the columns in Excel differently, I can do that as well.

p.s. - I'm currently not using any VBA whatsoever, just a straight mail merge.