Does polymorphism work in C++ without pointers / references?

Possible Duplicate:
Virtual Functions Object Slicing

let's consider:

#include <vector>
#include <iostream>
using namespace std;

struct A {
    virtual void do_it() { cout << "A" << endl; } 
};

struct B : public A {
    virtual void do_it()  { cout << "B" << endl; } 
};

int main() {
    vector<A> v;
    v.push_back(B());
    v[0].do_it(); // output is A
}

which function will be called? Basically is it possible to use polymorphism without pointers if no slicing is present?