HALLER (Gustav). - Lot 137

HALLER (Gustav). German acarologist, active in the second half of the 19th century, a specialist in mites (Acarina), whose work represented a critical continuation of that of Carl Ludwig Koch. Signed autograph letter, in German, with an attached French translation. April 16, 1877. 1 page, in-4. An interesting scientific letter devoted to the study of mites, and more specifically aquatic mites (Wassermilben), which were at the time very poorly studied. Responding to his correspondent, the author highlights the gaps in the existing bibliography: “with the exception of a few short monographs, nothing coherent has been published on the subject.” He emphasizes the lack of recent comprehensive works and laments the “extremely neglected” state of this branch of zoology. The letter takes a particularly critical turn when he discusses Koch’s work, acknowledging its scope while denouncing the superficiality of the classifications: difficulty in identifying species, confusion between sexes and developmental stages, artificial multiplication, or, conversely, the improper grouping of species (particularly within the genus Gamasus). He concludes by calling for a comprehensive revision of the order of mites, which he considers one of the most urgent tasks in contemporary zoology. A very interesting account of 19th-century taxonomic debates in the field of acarology, illustrating the transition from descriptive classifications to a more rigorous approach to species. Includes an old typewritten French translation. In good overall condition.