PL/SQL and parsing a variable for whitespace

I am trying to parse out a variable where it contains whitespace. For example: Lets say I have the variable called in_string varchar2(100) := 'This is a test'
I want to parse this variable so that every time it finds a whitespace character, it creates a substr. So after I parse it, I should have four substr, 'This', 'is', 'a', 'test'

How can I accomplish this processing?

Please send response via email, thank you.

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Bryan J. Gentile
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Business Data Services, Inc.
Glastonbury, CT  06033
Phone: (860) 633-3693 (ext. 3025)
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