use strict;
use warnings;
use Data::Dumper;

my @things = ( 1, 2, 3, "and", 4, 5, "and", 7, 8, 9 );
my @bucket;
my $counter = 0;
foreach my $elt ( @things )
{
  if ($elt eq "and")
  {
     $counter++;
  }
  else
  {
     push @{ $bucket[$counter] }, $elt;
  }
}
print "counter = $counter\n", Dumper(\@bucket);