EARLY INVESTIGATIONS. 13 



shallow water. A rfeum^ of opinions upon the rate of peat formation was also 

 given, and extensive extracts from De Luc, Poiret, Degner, Anderson, Walker, 

 and others were commented upon. As to the vegetation of mosses, he con- 

 cluded that many peat-bogs, when dug, are renovated by aquatic plants; that 

 the same species of plants have contributed and still contribute to the original 

 formation of many mosses; that many lakes in the north of Europe have been 

 converted into moss and then into meadows by the growth of these or similar 

 aquatic plants; that aquatic plants may be traced in most, if not all, moss; 

 and that many fertile plains, in the course of ages, have undergone changes 

 from arable lands to forests, from forests to lakes, from lakes to mosses, from 

 mosses to meadows, and from meadows to their original state of arable land. 

 He likewise supposed that many low levels, covered with wood, had been con- 

 verted into morasses. In citing examples of such changes, he also made use 

 of the term "succession," in the following sentence: (227) 



"The first is Low Modena, which seems to have undergone all these changes; 

 the second is the bog of Monela in Ireland, which seems to have been sub- 

 jected to a similar succession. Carr, in his 'Stranger in Ireland' (1806:190) 

 says: 'Stumps of trees are stiU visible on the surface of the bog of Monela; 

 imder these lies a stratum of turf 10 or 15 feet deep; xmder this a tier of pros- 

 trate trees is discovered; beneath these another stratum of earth is found of 

 considerable depth; and below this a great number of stumps of trees are 

 found, standing erect as they grew. Thus, there is a succession of three dis- 

 tinct forests lying in ruins, one above the other.' (229) There are other cir- 

 cumstances which render it equally probable that one generation has risen 

 upon the ruins of another. In many mosses one tier of roots appears perpen- 

 dicularly above another; yet both are fixed in the subsoil. In some even three 

 tiers appear, in succession, the one above another." (27) 



Bureau, 1825. — ^Bureau de la Malle (1825:353), attracted by the work of 

 Young on the effect of rotation upon crops, endeavored to trace the same 

 principle in woodland and meadow. As a landed proprietor in Perche, he 

 possessed unusual advantages for this purpose, both in the utiUzation of the 

 forests and in experiments designed to prove that the alternative succession 

 of plants is due to the long retention by seeds of the power of germination. 

 In cutting the woods of Perche, composed of Qusrcus, Fagus, Castanea, Ulmus, 

 and Fraxinus, only oaks and beeches were left as seed trees. The cut-over 

 areas came to be occupied by Genista, Digitalis, Senecio, Vacdnium, and 

 Erica, and finally by Betula and Populus tremula. At the end of 30 years, the 

 birch and aspen were cut, and quickly succeeded themselves. The oak and 

 beech returned only after the third cut, 60 years later, and became masters 

 of the area. Since there were no adjacent aspens and birches, the author 

 believed their seeds could not have been brought by the wind, and he con- 

 cluded that the seeds remained dormant in the soil for at least a century. He 

 noted also the reappearance of rushes, sedges, and grasses in clear areas in 

 the heath, and stated that he had observed the grasses and legumes of a 

 natural meadow successively lose and gain the preeminence for five or six 

 times in 30 years. The results of his observations and experiments are 

 summed up as follows : 



"The germinative faculty of the seeds of many species in a large number of 

 families can be retained for 20 years under water, or for at least a hundred 



