Since 1820, monographic writings, however, became more and more the practice. Among the volumes which treat certain branches of forestry monographically, the works of the masters of silviculture, _Cotta_, _Hartig_ and _Heyer_, based on their experiences in west and middle Germany, and of _Pfeil_, referring more particularly to North German conditions, were followed by the South German writers, _Gwinner_ (1834), and _Stumpf_ (1849). In 1855, _H. Burkhardt_ introduced in his classic _Säen und Pflanzen_ a new method of treatment, namely, by species, and after 1850, when the development of general silviculture had been accomplished, such treatment by species became frequent. Of more modern works on general silviculture elaborating the attempts at reform of old practices those of _Gayer_ (1880), _Wagener_ (1884), _Borggreve_ (1885), _Ney_ (1885), all writing in the same decade, are to be especially mentioned. In this connection should be also noticed _Fürst’s_ valuable collective work on nursery practice (_Pflanzenzucht im Walde_, 1882). At present the magazine literature furnishes ample opportunity to discuss the development of methods in all directions. The text books at present appearing seem to be justified by or intended mainly for the needs of the teacher and rarely for the practitioner. Such a text book is that by _Weise_. But the latest contributions to silvicultural literature by _Wagner_ (1907), and _Mayr_ (1909) are works of a new order, utilizing broader ecological knowledge. Other branches than silviculture were similarly first treated in comprehensive volumes and then in monographic writings on special subjects of the branch. The literature on _forest utilization_ covering the whole field, was enriched especially by _Pfeil_, _Koenig_, _Gayer_, and _Fürst_. The first investigation into the physical and technical properties of wood was conducted by _G. L. Hartig_ himself, followed by _Theodor Hartig_, and the subject has been most broadly treated by _H. Noerdlinger_ (1860). In later years, _Schwappach’s_ investigations deserve special mention. The question of means of _transportation_ gradually became also a subject capable of monographic treatment and a series of books came out on locating and building forest roads. _Braun_ issued such a book in 1855 for the plains country, and _Kaiser_ (1873) for the mountains, also _Mühlhausen_ (1876), who had been commissioned to locate a perfect road system over the demonstration forest at the forest academy of Muenden. Only within the last quarter of the century were railroads introduced into the economy of forest management. The first comprehensive book on the subject of logging railroads was issued by _Foerster_ (1885), and a later one by _Runnebaum_. _Stoetzer_ (1903) furnished in his compact style the latest discussion on the subject of roads and railroads.