The reference to "Scotch patience" applies an assumed quality genetically attributed to a specific ethnicity.  Notions such as these appear in naturalistic novels such as Frank Norris' McTeague and Harold Frederic's The Damantion of Theron Ware.  Naturalistic novels "tend to emphasize either a biological or a socioeconomic determinism," often based on assumptions regarding a set of assumed qualities associated with a specific ethnic group (Harmon and Holman 338).  For example, in the case of Norris' McTeague, Zerkow's interest in money apparently is a result of him being Jewish.  Note that Twain is not a naturalistic author, and Pudd'nhead Wilson is certainly not a naturalistic novel.