A correspondent sent me a link to the Project Gutenberg online edition of The German Element in Brazil by Benjamin Franklin Schappelle, first published in 1917 (Americana Germanica Press, Philadelphia). It starts off with a history of German immigration (going back to the mid-16th century) and a description of the German colonies in the various states, then gets down to business:
The settlers, largely drawn from the agricultural class, naturally brought with them from Europe a variety of German dialects. These were more or less preserved depending on the relative isolation of the colonies. In cases where a considerable and constant influx of settlers either by direct or indirect immigration was kept up after the first years of the history of any particular colony the original dialect largely gave way to a modified form of High German, due primarily to the normalizing influence of the German school and church. Such is the case in the ‘Stadtplätze’ of Dona Francisca, Blumenau, Santa Cruz and São Lourenço.
The preceding statements are intended to present, as it were, the background or basis on which the new dialect was developed. We now come to the most potent influence in the formation of that dialect. It is the Brazilian Portuguese, a language which has no connection with the Germanic group. In this point, therefore, our case differs radically from that of the student of the German dialects which have been developed in North America.
It explains how German words were changed (including family names: “Emmich became M’. The Portuguese could not pronounce the ‘-ich’ and consequently it dropped off, resulting in the formation of what is probably one of the shortest family names in existence”) and provides sample texts and a glossary; apparently so many Brazilian Portuguese words were borrowed that the dialect could be incomprehensible to visitors from German-speaking parts of Europe.