338 THE BOTANISTS OF PHILADELPHIA. 



peculiar sub-tropical flora of that State. His studies upon 

 the bald cypress of the Florida swamps are especially note- 

 worthy, as combining both morphological and physiological 

 research. He clearly demonstrated, both by experiments in 

 the greenhouse, and by a microscopic study of the peculiar 

 knees produced on this tree and on other plants living or 

 grown under similar conditions, that the protuberances on 

 the roots are breathing organs, and are produced in direct 

 response to the action of the environment. 



His original work — teaching and direction of the bio- 

 logical school at the University, to which he was appointed 

 on the death of the venerable scientist. Dr. Joseph Leidy — 

 occupied fully his time until 1893, when Professor Wilson 

 made the proposition to one or two public-spirited gentle- 

 men on September 7, 1893, to procure from the foreign 

 exhibitors at the World's Columbian Exhibition the fine 

 collections which had been so carefully gathered together 

 for exhibition purposes. Later, City Councils took hold of 

 the matter, and with an appropriation of $10,000, Dr. 

 Wilson, resigning the Directorship of the Biological School, 

 went to Chicago and succeeded in securing a vast collection 

 of various objects from Mexico, Costa Rica, Guatemala, 

 British Guiana, Ecuador, and various South American, 

 European and Asiatic States. Dr. Wilson succeeded in 

 organizing a vast museum of economic products during the 

 two years' leave of absence granted to him by the Univer- 

 sity — a museum occupying the former offices of the Penn- 

 sylvania Railroad Company, with a floor space of some 

 200,000 square feet. As Director of this Museum, Dr. 

 Wilson's time is very fully occupied with the executive 

 work of the institution, so much so that he resigned his 

 professorship in the University of Pennsylvania. 



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