En este estudio aportamos mayor evidencia en sustento de la hipotesis que planteamos por primera vez en el ano 2003 de que el siglo XIX constituye el inicio de un tercer periodo evolutivo para la lengua espanola. Discutimos en primer lugar que la periodizacion que suelen establecer los manuales y tratados de historia del espanol, en dos grandes etapas: la "medieval" (siglos XII al XV) y la "moderna", que arranca en los siglos XVI-XVII y se prolonga hasta nuestros dias (Cano Aguilar 1988; Lapesa [1942] 1981; Penny 1993; Spaulding 1943) es prematura, dada la falta de estudios del camino evolutivo que recorrio el espanol despues del siglo XVII. Ofrecemos tambien un panorama breve de los retos que enfrenta las tareas de periodizacion y los tipos de evidencia, de caracter interno y externo, que suelen presentarse para establecer las etapas evolutivas de una lengua y delimitar sus fronteras. Presentamos, en apoyo de nuestra hipotesis, una lista abundante de cambios linguisticos, que atanen muchos de ellos a zonas nucleares de la gramatica y que tienen su momento de inicio o expansion en el siglo XIX. Esbozamos tambien los angulos que hacen del siglo XIX un candidato idoneo, desde una perspectiva externa, para constituir el momento inaugural de una tercera etapa evolutiva de la lengua espanola.
In this work we provide further evidence in support of the hypothesis that we first formulated in 2003 regarding the association of the 19th century with the beginnings of the third historical period of the Spanish language. We first establish that the traditional division of the history of the Spanish language in two major periods � "medieval" Spanish (12th to 15th centuries) and "modern" Spanish, starting during the 16th and 17th centuries and continuing until the present (Cano Aguilar 1988; Lapesa [1942] 1981; Penny 1993; Spaulding 1943)� is premature, considering the shortage of studies dedicated to the evolution of Spanish after the language reached its so-called Golden Age in the 17th century. We also offer an overview of the challenges implied in defining the periods of a language, in conjunction with the types of evidence, both internal and external, which scholars tend to appeal to when seeking to mark such temporal boundaries. We then proceed to discuss a plentiful series of linguistic changes that give support to our hypothesis, insofar as the changes affect central areas of the Spanish grammar and develop in the 19th century. We conclude with a short reflection on the historical circumstances that were favorable to the establishment of the 19th century as the inaugural moment of the third period of Spanish.