Witte’s studies show that, in Alsace,[34] the delimitation of the Germanic and Romanic domain is somewhat more complicated than in Lorraine. Valuable clues are generally afforded by toponymic data. The Alemanni are responsible for the suffix “heim.” Towns and villages with names bearing this suffix are restricted to the plain. The dividing line extends on the west to the sub-Vosgian foreland and attains the forest of the Haguenau on the north. This last section corresponds to the beginning of an area of Frankish colonization having its center at Weissenburg. The suffix “ingen,” which occurs in place names of southern Alsace, is likewise Alemannic. It is supposed to correspond, however, to a later period of settlement. The ending “weiler” accompanies the names of villages found on the heights. These data led Witte to assume that the Celto-Roman natives of the plains were thrust back towards the mountains by the Alemannic invasion proceeding from the east. The designation “weiler,” which is also spelled “weyer,” “weyr” and “wir,” indicates the mountain sites to which the population of the plain was repelled by the Germanic flow. The Vosges mountains have thus been a place of refuge against Germanic aggression. Witte’s researches point to the probable peopling of the Alsatian slopes of the Vosges by tribes speaking a Romanic language during the invasions of Teutonic barbarians. The so-called Welsh element appears to be a Celto-Roman remnant of the population of the locality.[35] The character of Alsace-Lorraine as a connecting region between two great European nations is shown also by demographic studies.[36] Life in the provinces is accompanied by conditions which prevail in Germany or France. The excess of births over deaths, which maintains itself on an average at about 10 per 1,000, is lower than in any other part of the German Empire. The rate of birth has decreased from 36 to 28 per 1,000 in spite of an increase in the population. The tendency of the inhabitants to emigrate is evinced by the large number of uninhabited houses. The decrease in the native population is largely due to the desire of many of the inhabitants to emigrate to French soil. In 1875 the proportion of native-born inhabitants amounted to 93 per cent of the total population. In 1905 it did not exceed 81 per cent. The strictly German element had grown from 38,000 in 1875 to 176,000 in 1905. Fully 90 per cent of these are native-born Prussians. Among them the teaching of French to children has increased. Molsheim, in Lower Alsace, and Ribeauvillé, in Upper Alsace, are centers for the study of French. In recent years German immigrants have become the preponderant element of the province.