particleSystem.Play(); wont start

i wrote this code which i thought should work.
the thing is that the particle wont start showing and i cant figure out why.
The emitter should emitt for like 2 seconds and then stop.

im guessing that it is because it lies in the void Update function and it starts and stops in a millisecond. but i dont know.

here is the script:

using UnityEngine;
using System.Collections;

public class BloodonHitP1: MonoBehaviour {

	public Hit hit;

	void Start () {


	// Update is called once per frame
	void Update () {
		if (hit.wonTwo){



its ParticleSystem.Play(); i think