In preparation for the process of sorting out and distributing to each sex and age appropriate forms of exercise Spiess thought it necessary first of all to collect, analyze, and classify the whole mass of possible positions and movements of the body. This he endeavored to do in his “System of Gymnastics” (_Die Lehre der Turnkunst_), but without seeking at the same time to separate the useful from that which is unessential or undesirable. The book is not intended, therefore, as a practical guide for the teacher. That function was reserved for his second work, the _Turnbuch für Schulen_, which has been a mine of instruction and suggestion for authors of later manuals. Here he leads gradually from the simplest exercises to the most difficult combinations, pointing out what material is to be used for each sex and age, and explaining the method to be pursued during the lesson hour. He devised new forms of apparatus on which the whole class, or a considerable fraction of it, could work at once under the teacher’s eye and at his command. The “Free Exercises” and the “Class Exercises in Marching” (_Ordnungs-_ or _Gemeinübungen_) which he elaborated were a fresh contribution to the stock of German gymnastics, and with his simpler exercises on apparatus supplied material for girls and younger boys. His musical gifts[72] rendered possible that rhythmical arrangement of the free exercises which has continued to be so conspicuous a feature in the teaching of his followers ever since, and enabled him also to combine artistically certain marching or dancing or other rhythmical movements into a fixed series which could be executed by pupils to the accompaniment of some familiar song, or other musical composition, as in the case of the Miller-_Reigen_ and the whole group of _Lieder-_ and _Tanz-Reigen_.[73] BIBLIOGRAPHY. Euler’s “Encyklopädisches Handbuch des gesamten Turnwesens” and “Geschichte des Turnunterrichts” (see p. 82), and the following articles in the _Neue Jahrbücher für die Turnkunst_ (NJT), _Deutsche Turn-Zeitung_ (DTZ), and _Monatsschrift für das Turnwesen_ (MT): Wassmannsdorff in NJT 1855: 330-334 and 1858: 81-90; and in DTZ 1859: 22-23 and 1863: 137-140. Lion in DTZ 1858: 91-93, 98-99, and 102-103. Marx in NJT 1885: 57-66. Schmeel in DTZ 1910: 82-85, 97-101, 117-120, and 133-136. Schmuck in DTZ 1911: 453-457. Neuendorff in MT 1910: 122-128.