September 7, 1917] 



SCIENCE 



245 



The most illustrious botanist of the first half of 

 the last century to give attention to fungous 

 plants was L. D. von Schweinitz, of Salem, N. C, 

 and later of Bethlehem, Pa. He became a member 

 of the American Philosophical Society just one 

 hundred years ago, and some time later published 

 in the Transactions of the society the earliest list 

 of "North American Fungi." This attempt at a 

 comprehensive list for the whole country was not 

 again made until the present time, but now the 

 work is in progress, divided among a number of 

 men. The rusts are being listed by Professor J. 

 C. Arthur, LL.D., of Purdue University, Lafayette, 

 Ind. He now presents to the society an estimate of 

 Ton Schweinitz 's notable achievement with this 

 group of fungous plants. Of the four thousand spe- 

 cies of fungi on Schweinitz 's list 135 were rusts, a 

 class of parasitic fungi of the greatest economic im- 

 portance. All of Schweinitz 's collection, now de- 

 posited at the Philadelphia Academy of Sciences, 

 has been critically examined and identified, and a 

 record made of the present knowledge relating to 

 each form. Dr. Arthur pays a high tribute to the 

 remarkable showing made by Schweinitz, to his 

 great accuracy and industry, and to the eminent 

 services which he rendered to American botany. 



Ecology and physiology of tlie red mangrove: H. 



H. Bowman, fellow in botany. University of 



Pennsylvania. (Introduced by Professor Harsh- 



berger.) 



The mangroves have been noted by the ancient 

 Greeks in early classic literature. Nearchus, the 

 admiral of Alexander the Great, mentioned them 

 as being observed on Alexander's expedition into 

 Asia. They were found by the Greeks growing 

 along the shores of the Persian Gulf and the Red 

 Sea. Theophrastus, the pupil of Aristotle, wrote 

 concerning them as well as Pliny, and many 

 medieval and later travelers and explorers. An 

 examination has been made of the microscopic 

 structure of the various tissues of these trees from 

 material collected in the Gulf of Mexico, along the 

 lower Florida Keys. Particular attention has 

 been paid to the presence of intercellular stone 

 cells and to the occurrence of tannin cells. The 

 physiological relations of transpiration and ab- 

 sorption of these plants growing in sea water and 

 all dilutions of it, as well as fresh water, have been 

 studied, and the law deduced that the rate of 

 transpiration varies directly with the concentra- 

 tion of the medium. Biochemically, it has been 

 shown that there is a defiidte relation between the 

 amounts of sugar and tannin in the hypocotyls at 

 different stages of growth of the plants. Ecolog- 



ical factors show their effect on various tissues, 

 particularly those of the leaves, e. g., the variation 

 in leaf thickness and structure in oflf-shore, in- 

 shore, salt-water and fresh-water plants. Geolog- 

 ically, the mangroves are of importance in build- 

 ing up land and increasing the area of dry land on 

 islands and continents in the tropics. Under eco- 

 nomic considerations it may be stated that the 

 tannin contained in the tissues is used for tanning 

 leather. The wood is the source of an excellent 

 charcoal, but chiefly the plants have been used in 

 keeping up embankments along the seashores and 

 in building dams and dykes. The distribution of 

 these trees along the Florida peninsula and keys is 

 plotted in a series of maps. 



Reception from eight to eleven o'clock at the 

 hall of the Historical Society of Pennsylvania, 

 when George Ellery Hale, Ph.D., Sc.D., LL.D., 

 F.R.S., director of the Solar Observatory of the 

 Carnegie Institution of Washington, at Mt. Wilson, 

 Calif., gave an illustrated lecture on ' ' The work of 

 the Mt. Wilson Observatory." 



APRIL 14 



William B. Scott, Sc.D., LL.D., "Vice-president, in 

 the chair 



Biochemical studies of the pitcher liquid of Ne- 

 penthes: Joseph S. Hepburn, M.S., Ph.D. (In- 

 troduced by Professor Harry F. Keller.) 



The National Research Council and its opportuni- 

 ties in the field of chemistry: Marston T. 

 BoGERT, Ph.B., LL.D., professor of organic 

 chemistry, Columbia University. 



The South American Indian in his relation to geo- 

 graphic environment : William Ctjrtis Fakabee, 

 A.M., Ph.D., curator of American Section of 

 Museum, University of Pennsylvania. (Intro- 

 duced by Mr. Henry G. Bryant.) 



Interrelations of the fossil fuels: J. J. Stevenson, 

 Ph.D., LL.D., emeritus professor of geology, 

 New York University. 



This paper deals with the Cretaceous coals, which 

 are vastly more important in the United States 

 than in all the rest of the world. After descrip- 

 tion of stratigraphical and chemical conditions ob- 

 served in the typical areas, an effort is made to 

 present the characteristic features in such fashion 

 that the relations to peat and the Tertiary coals 

 may be made clear. 



The distribution of land and water on the earth: 

 Harry Fielding Reid, Ph.D., professor of dy- 

 namic geology and geography, Johns Hopkins 

 University. 



