SphereEmitters.cs

using UnityEngine;
using System.Collections;

public class SphereEmitters : MonoBehaviour {

    public GameObject sphere;

    public void OnEnable()
    {
        // Disable the sphere at startup:
        //sphere.SetActive (false);
    }

    public void activateSphere()
    {
        Animator sphereAnimator = sphere.GetComponent<Animator> ();
        sphereAnimator.SetTrigger ("Activate");
        sphere.GetComponent<MeshRenderer> ().material.SetFloat ("_AppearAmount", 0);

        // Make sure to show the sphere:
        sphere.SetActive (true);
    }
}