function envia(url, metodo, modo)
{
    var login = document.getElementById('form1').login.value;
    remoto  = new ajax();
    xmlhttp = remoto.enviar(url + "?login=" + login, metodo, modo );
    if(xmlhttp) {
        document.getElementById('login').className = 'erro';
        document.getElementById('alerta').className = 'alerta2';
        document.getElementById("alerta").innerHTML = "ja consta na base";
        document.getElementById("botao").innerHTML = '<input name="botao" type="submit" class="botao" disabled="disabled"  value="cadastrar" />';

    } else {
        document.getElementById('login').className = 'texto';
        document.getElementById('alerta').className = '';
        document.getElementById("alerta").innerHTML = "Não consta na base";
        document.getElementById("botao").innerHTML = '<input name="botao" type="submit" class="botao"  value="cadastrar" />';

    }    
}