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SCIENCEVOL. 91 FRIDAY, APRIL 26, 1940 No. 2365

The American Association for the Advancement of DR. R. E. HAIST and PROFESSOR C. H. BEST.Science: Toxicity of Extracts of the Postpartum Rabbit

Some Soil Factors Affecting Tree Growth: PRO- Uterus: DR. BORIS KRICHESKY and WILLIAM POL-FESSOR ROBT. M. SALTER ............................................................ 391LOCK. The Biological Activity of SyntheticPanto-

thenic Acid: DR. DONALD PRICE and OTHERS ...... 410Scientific Events:

Mathematical Symposium at the University of Scientifc Apparatus and Laboratory Methods:Notre Dame; Centennial Celebration of the Found- Improvements in the Harvard Spring Kymograph:ing of the Department of Chemistry of Western HUGH B. MCGLADE. A Plastic Cover Glass Iso-Reserve University; Appointments in the Regional butyl Methacrylate: HAROLD C. O'BRIEN and PRO-

ofU. S. DepartmentofAgricul- ROBERTT.HANCE .................................................................. 412

ture; The Eighth American Scientific Congress;PhilosophicalSociety .................................... ...................................................................................................... 8

Scientific Notes and News .................................................................. 401

Discussion:The Question of the Cell Theory: PROFESSOR JOHN SCIENCE: A Weekly Journal devoted to the Advance-P. TURNER. Electricity Elicited by an Organic ment of Science, edited by J. MCKEEN CATTELL and pub-Chemical Process: DR. D. NACHMANSOHN. Again lished every Friday byScience in China: DR. GEORGE W. HUNTER, III. THE SCIENCE PRESSThe Programs of Scientific Meetings: C. B. MEN-

DENHAL.404 Lancaster, Pa. Garrison, N. Y.DENHALL .............................................................................................................. Lancaster, a. garrison,

New York City: Grand Central TerminalReports:

Annual Subscription, $6.00 Single Copies, 15 Cts.Pure and Applied Science at the Mellon Institute: A al Subscription, $6.00 Single Copies, 15 Cts.DR. W. H. HAMOR ........................................ 407 SCIENCE is the official organ of the American Associa-

tion for the Advancement of Science. Information regard-Special Articles: ing membership in the Association may be secured from

the office of the permanent secretary in the SmithsonianFactor Affecting the Insulin Content of Pancreas: Institution Building, Washington, D. C.

SOME SOIL FACTORS AFFECTING TREE GROWTH1By ROBT. M. SALTER

PROFESSOR OF SOILS, THE OHIO STATE UNIVERSITY, AND CHIEF IN AGRONOMY,OHIO AGRICULTURAL EXPERIMENT STATION, WOOSTER

IT is just one hundred years since Liebig, in hisfamous report to the British Association upon thestate of organic chemistry, delivered with vitriolicinvective the death sentence to the theory held by con-

temporary plant physiologists that plants obtain theircarbon from the soil. He did it in these words, "Allexplanations of chemists must remain without fruit,and useless, because, even to the great leaders of physi-ology, carbonic acid, ammonia, acids and bases aresounds without meaning, words without sense, termsof an unknown language, which awaken no thoughts

1 Address of the retiring vice-president and chairmanof the Section on Agriculture, American Association forthe Advancement of Science, Columbus, Ohio, December30, 1939.

and no associations." How different is the state ofaffairs to-day, how ramshackle have become the oncehallowed walls dividing the natural sciences, must beapparent when an agronomist deigns to rise before agroup of horticulturists and foresters and speak on aprogram dealing with the physiological aspects of treegrowth. Fortunately it appears now well establishedthat both fruit and forest trees send their roots intothe soil, that natural medium which until recent timeswas peculiarly the domain of the agronomist. For-tunately, also, the interactions of the soil and treeappear not to differ materially from the interactionsof the soil and agronomic crops. In fact, except inthe degree of surface manipulation involved and in the