#!/usr/bin/perl -w
use strict;
use Data::Dumper::Simple;

my @lines;

while (<DATA>) {
    chomp;
    @lines = split (/(?<=\.)/, $_);
}

print Dumper(@lines);

__DATA__
First line. Second Line. Third line. Fourth line.

##</code><code>##

@lines = (
           'First line.',
           ' Second Line.',
           ' Third line.',
           ' Fourth line.'
         );