1897.] Proceedings of Scientific Societies. 563 
May 3, 1897-—Twenty-one persons present. Mr. H. Von Schrenk 
spoke of the respiration of plants, with special reference to the modifi- 
cation of those growing with their roots submerged in water. The 
lecture was illustrated by a demonstration of the liberation of carbon 
dioxide in respiration, from the roots of an ordinary flowering plant and 
freshly gathered fungi, and the more usual aerenchyma structures were 
made clear by the use of lantern slides. 
Professor F. E. Nipher described a simple means of measuring the 
resistance of a tube to the flow of a current of air, when compared with 
an accepted standard, by the use of a tubular device similar in princi- 
ple to the Wheatstone bridge used in electrical instruments, the appa- 
ratus, in the present instance, consisting of parallel tubes filled with air, 
connected by a tubular bridge, in the middle of which a drop of water 
was placed, so as to change position with the variations in the flow of 
air on the one hand or on the other— WILLIAM TREALEASE, Secretary. 
Society of Natural History of Delaware.—At the regular 
meeting of the Society, held Monday, February 1st, Edward Tatnall 
presented eleven volumes of botanical works,—these included “An In- 
troduction to the Science of Botany,” by the late James Lee, published 
in London in 1810; “ Manual of Botany for North America,” by Prof. 
Amos Eaton, published in 1833; “An Introduction to Systematic and 
Physiological Botany,” by Thomas Nuttall, published in 1830. Miss 
Sarah M. Fell gave a collection of the ferns of New Castle County, 
Delaware. 
Mr. Walter D. Bush, of the Ornithology Committee, reported having 
seen no black-birds as yet. They are usually here at an earlier date. 
He had not been able to find any blue-birds this winter. 
Edward Tatnall reported having found hepatica, sanguinana and 
violets in bloom December 8th, and Symplocarpus in full bloom Jan- 
uary 13th. 
Mr. John T. Pennypacker gave an account of the researches of Prof. 
E. D. Cope among the debris in the rock-cleft at Port Kennedy. 
Dr. Wm. C. Pierce read a valuable paper on “ Night Lights of 
Insects.” . 
The Fourth Triennial Congress of American Physicians 
and Surgeons.—The Fourth Triennial Congress of American Physi- 
cians and Surgeons was held in Washington, D. C., May 4th, 5th and 6th. 
The first general session was held on May 4th, at the Columbia Theatre, 
where the members were welcomed in an address by Dr. L. C. Gray, 
the Chairman of the Executive Committee. After the address the sube 
