open my $fh, '<', $file or die "failed open file: $!";
my $arr = [];

my $beginParagraph = 'begin';   # mark start the particular paragraph
my $endParagraph = 'end';      # mark end the particular paragraph

while ( <$fh> ){
      if ( /$beginParagraph/ .. /$endParagraph/ ) {
      push @{ $arr->[$.] }, split /\./;  # i assume string end '.' 
      }
}