The 1841 British edition omitted the conjunction and here, undoubtedly by accident since either reading is theoretically possible. The subsequent LDS edition (1849) restored the and. Elsewhere the text has 12 other examples of “and for this cause”. There are also examples of “for this cause” preceded by other connectors (such as and now, therefore, wherefore, and even for itself ). There are also a couple of examples where “for this cause” begins a sentence:
The critical text will maintain the earliest text with the and here in Alma 17:35.
Summary: Maintain in Alma 17:35 the connective and before “for this cause”, the reading of the earliest textual sources.