January 7, 1910] 



SCIENCE 



39 



matter are aerobic organisms, principally plants; 

 anaerobic forms being much less active and seem- 

 ingly wanting in many peat beds. Over most of 

 the United States, peat is formed only where the 

 ground-water level is above or veiy near the soil 

 surface, because it is only through saturation 

 that the air and the more actively destructive 

 organisms are excluded and vegetable accumula- 

 tions partially preserved. The numbers and kinds 

 of anaerobic organisms and the decomposition re- 

 sulting from their activities seem also to be re- 

 duced by the presence of gases like hydrogen 

 sulphide and methane and of colloidal and soluble 

 poisonous substances resulting from the decom- 

 position in progress. Most peat beds show a much 

 greater amount of decomposition above the water 

 level than below it. 



The two types of peat deposits discussed were 

 those formed ( 1 ) in depressions below the ground- 

 water level, ponds and lakes; (2) where the soil 

 surface was at or slightly above the ground-water 

 level, poorly drained flat areas. 



In ( 1 ) the major part of the material is laid 

 down under water through the growth of aquatic 

 plants. These are primarily governed in the 

 depth to which they can grow below the water 

 surface by the distance to which enough light can 

 penetrate for the minimum requirement to enable 

 them to establish themselves. Few species reach 

 twenty feet even in clear water, and this is re- 

 duced by any suspended or dissolved colored mat- 

 ter. Peat formation is slow at maximum depths 

 at which plants grow, and more rapid in shallower 

 water — hence the deposits often take the form of 

 terraces, with steep outer faces. The peat at 

 different depths is chiefly or wholly formed by 

 definite plant associations that arrange them- 

 selves zonally around the open water, according 

 to their tolerance of poor light, low temperature 

 and other unfavorable conditions. Free-floating 

 plants of all types may form additions to any 

 part of deposits or make up a large part of any 

 given one. 



When the surface of the accumulated debris 

 rises nearly to the level of the water, turf-forming 

 plants may invade it and form a permanent cover. 

 Shrubs, coniferous trees and sphagnum moss may 

 establish themselves when the surface is about a 

 foot above the permanent water level, and the 

 latter may then build up the deposit for a few 

 feet. The sphagnum-covered peat bed is more 

 common at the north than in the south, where 

 shrub and tree-covered deposits are more common. 



The plants that form peat beds on flat areas 



are those able to endure excess of water, and 

 probably toxic substances about their roots. 

 Those found in a particular locality will depend 

 on the permanent relation of the ground-water 

 level to the soil surface, and may be mosses, sedges, 

 grasses, shrubs or trees, or mixtures of all these. 

 If the water level rises as the peat accumulates, 

 as seems often to happen, the same plant asso- 

 ciations may form the entire deposit. If the peat 

 builds faster than the water level rises, the sig- 

 nificant plants will change until a forest associa- 

 tion is developed. 



If the water level rises faster than the peat, 

 pond conditions may be developed. In any case, 

 peat beds will be of homogeneous structure only 

 where the water level rises with the peat, and it 

 is only on such deposits that the plant association 

 growing on the surface is significant of the struc- 

 ture and quality of the peat below. 



W. W. Stockbergek. 

 Corresponding Secretan/ 



THE TOEREY BOTANICAL CLUB 



The meeting of October 27, 1909, was held at 

 the New York Botanical Garden and was called 

 to order at 3:30 p.m. by Dr. E. B. Southwick. 



About forty persons were present. After the 

 reading of the minutes of the preceding meeting, 

 the scientific program was presented, the first 

 contribution being made by Mrs. N. L. Britton, 

 who spoke on " Arctic Mosses." The speaker's 

 remarks were based on studies of mosses sent from 

 the American Museum of Natural History to the 

 New York Botanical Garden for determination. 

 They were collected by Commander Robert E. 

 Peary in Grant Land in 1902, and by Dr. L. J. 

 Wolf at Wrangle Bay, Lincoln Bay and Grant 

 Land in 1906. The Peary collection includes 62 

 bryophytes, of which 57 were mosses, represent- 

 ing 24 genera, and 5 were hepaties. 



Specimens of flowering plants were also exhib- 

 ited which have recently been acquired by the New 

 York Botanical Garden through the courtesy of 

 the Peary Arctic Club from the American Mu- 

 seum of Natural History. 



The collection consists of herbarium specimens 

 made on the late expedition of Commander Peary 

 to the North Pole and were collected mostly by 

 Dr. J. W. Goodsell. While some of these were 

 obtained on the northern coast of Labrador, the 

 majority were collected on Grant Land, in the 

 northern portion of Ellesmere Land, an island off 

 the coast of Greenland. One of the packages con- 

 tained specimens from perhaps the most northern 



