Observable inside a for

I am practicing ionic2, I am doing services with observables, in one part I made a for and within that for call another service but it seems that it stops the for and is counting the total of the array. Is it because of the observable that stops it? I show you how I am doing it:

menu.ts

getMenusAjax():Observable<any>{
  return this.http.get('http://localhost:3000/menu/todos')
    .map(res => res.json());
}

contenido.ts

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';

@Injectable()

export class contenidoServices{
  constructor(public http: Http){}

  getContenidoImagenes(id):Observable<any>{
    return this.http.get('http://localhost:3000/imgcont/${id}')
        .map(res => res.json());
  }
}

page2.ts

import { Component } from '@angular/core';

import { NavController, NavParams } from 'ionic-angular';

import { Me } from '../../app/commons/me';
import { MenuServices } from '../../app/services/menu';
import { contenidoServices } from '../../app/services/contenidos';

@Component({
 selector: 'page-page2',
 templateUrl: 'page2.html'
})

export class Page2{

  selectedItem: any;

  constructor(
   public navCtrl: NavController,
   public navParams: NavParams,
   private menu: MenuServices,
   private contenido: contenidoServices
  ){
    var contenidoDate = navParams.get('item');

    for (var j = 0; j < contenidoDate.length; ++j) {
      console.log(j);
      let images = contenido.getContenidoImagenes(contenidoDate[j].id);

      images.subscribe(
        res => {
          console.log(j);
          if(res != 2) {
            console.log(res);
            console.log(contenidoDate[j]);
          }
        },
        err => {console.log(err);}
      );
    }
    this.selectedItem = navParams.get('item');
  }
}

Result in console, numbers 0 and 1 print before calling the service and 2 prints when the service has already been called