EAELY INVESTIGATIONS. 9 



SO still makes an addition: Sometimes the tops of flags and grass are inter- 

 woven on the surface of the water, and this becomes by degrees thicker, till 

 it Ues like a cover on the water; then herbs take root in it, and by a plexus 

 of the roots it becomes very strong, so as to bear a man. These may be easily 

 turned into a meadow, as I have seen several times, merely by clearing a 

 trench to let the water run away. Trees are found sound and entire in them, 

 and those birch or alder that are very subject to rot. I have seen of the trees 

 half sunk into the bogs and not quite covered. They are generally found at 

 the bottom, not only of the wet, but even of the dry red bogs." 



Degner, 1729. — Degner's dissertation upon peat-bogs, especially those of 

 Holland, appears to have been the first comprehensive treatise upon this 

 subject, though he cited Schook's "Tractatum de Turfis" (1658), and Patin's 

 "Trait^ de Tourbes Combustibles" (1663), as still earHer works. Degner 

 combated the assimiption that "moss is formed of decayed wood" by the 

 following arguments : 



" 1. It is contrary to the common opinion of the inhabitants of Holland. 



"2. Trees are not found in every moss. 



"3. Trees are often found buried where no moss is formed. 



"4. Where trees abound are the fewest mosses. They seem rather 



to retard than expedite the formation of mosses. 

 "5. Some mosses are found to be 30 feet deep before we reach the 



wood; it seems incredible that such immense quantities of 



that matter could be formed of wood. 

 "6. If forests are converted into moss, the greatest part of Muscovy, 



Tartary and America, and other woody uncultivated regions, 



would, long ere now, have undergone that change, which is 



not the case." 



Degner described the peat-bogs of Holland minutely, and asserted that they 

 are often renewed when dug. He stated that the pits and ditches are fiUed 

 with aquatic plants, and that these are converted into peat. He found also 

 that when a large pit was dug, and a large sheet of water was left exposed to 

 the winds, the growth of aquatic plants was retarded and the renewal of the 

 moss checked; while in small pits aquatics developed rapidly and the renewal 

 of the moss was correspondingly rapid. He mentioned as well-known facts 

 the filling of a ditch 10 feet wide by 7 feet deep by aquatic plants in 10 to 30 

 years to such a degree that men and cattle could safely pass over it, and the 

 digging of peat where a navigable lake once existed. 



Buff on, 1742. — Buff on seems to have left the first clear record of the succes- 

 sion of forest dominants, and of the effect of light and shelter on the process: 



"If one wishes to succeed in producing a forest, it is necessary to imitate 

 nature, and to plant shrubs and bushes which can break the force of the wind, 

 diminish that of frost, and moderate the inclemency of the seasons. These 

 bushes are the shelter which guards the young trees, and protects them against 

 heat and cold. An area more or less covered with broom or heath is a forest 

 half made; it may be ten years in advance of a prepared area. (234) 



"The best shelter in wet soil is poplar or aspen, and in dry soil Rhus, for the 

 growth of oak. One need not fear that the sumac, aspen or poplar can injure 

 the oak or birch. After the latter have passed the first few years in the shade 

 and shelter of the others, they quickly stretch up, and suppress all the sur- 

 rounding plants. (237, 238). 



