多态性和Protobuf-net的串行化和反串行化

我正在尝试使用protobuf-net来序列化对象。我不确定我试图用继承做的事情是否得到支持，但我想我应该检查一下，看看是不是支持，或者我只是做错了什么。

从本质上讲，我试图序列化一些子类，然后反序列化它，但只使用基类引用。演示：

using UnityEngine;
using System.Collections;
using ProtoBuf;
public class main : MonoBehaviour
{
    // If I don't put "SkipConstructor = true" I get
    // ProtoException: No parameterless constructor found for Parent
    // Ideally, I wouldn't have to put "SkipConstructor = true" but I can if necessary
    [ProtoContract(SkipConstructor = true)]
    [ProtoInclude(1, typeof(Child))]
    abstract class Parent
    {
        [ProtoMember(2)]
        public float FloatValue
        {
            get;
            set;
        }
        public virtual void Print()
        {
            UnityEngine.Debug.Log("Parent: " + FloatValue);
        }
    }
    [ProtoContract]
    class Child : Parent
    {
        public Child()
        {
            FloatValue = 2.5f;
            IntValue   = 13;
        }
        [ProtoMember(3)]
        public int IntValue
        {
            get;
            set;
        }
        public override void Print()
        {
            UnityEngine.Debug.Log("Child: " + FloatValue + ", " + IntValue);
        }
    }
    void Start()
    {
        Child child = new Child();
        child.FloatValue = 3.14f;
        child.IntValue   = 42;
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        // I don't *have* to do this, I can, if needed, just use child directly.
        // But it would be cool if I could do it from an abstract reference
        Parent abstractReference = child; 
        ProtoBuf.Serializer.Serialize(ms, abstractReference);
        ProtoBuf.Serializer.Deserialize<Parent>(ms).Print();
    }
}

该输出：

Parent: 0

我希望它输出的是：

Child: 3.14 42

这可能吗？如果是这样，我做错了什么？我在SO上读过关于继承和protobuf-net的各种问题，它们都与这个例子有点不同（据我所知）。

ProtoBuf.Serializer.Serialize(ms, abstractReference);
ms.Position = 0; // <========= add this
ProtoBuf.Serializer.Deserialize<Parent>(ms).Print();