Android :: Error With Putting Extra Object

I'm trying to pass an object from an activity to another activity. In the first activity i do:

Intent intent = new Intent(this, SecondsActivity.class); intent.putExtra("package.class", SerializableObject);

And in the second activity:

Class object = (Class) extras.getSerializable("package.class"); objetc.modifySomething(2432);

Intent intent = new Intent(this, ThirdActivity.class); intent.putExtra("package.class", SerializableObject);

But if i modify the object in the second activity, it fails when i send this object to a third activity.Why does it fail? What am i doing wrong? I just need to pass objects between diferent activities because i have an object which contains many information, and creating a Boundle would be very big and ugly in my code.