Question mark
In the early 13th century, when the growth of communities of scholars (universities) in Paris and other major cities led to an expansion and streamlining of the book-production trade, punctuation was rationalized by assigning Alcuin's stroke-over-dot specifically to interrogatives; by this time the stroke was more sharply curved and can easily be recognized as the modern question mark.
Q source
In 1838 another German, Christian Hermann Weisse, took Schleiermacher's suggestion of a sayings source and combined it with the idea of Markan priority to formulate what is now called the Two-Source Hypothesis, in which both Matthew and Luke used Mark "and" the sayings source. Heinrich Julius Holtzmann endorsed this approach in an influential treatment of the synoptic problem in 1863, and the two-source hypothesis has dominated ever since.