72 



SCIENCE 



[N. S. Vol. XL VI. No. 1177 



live even longer than they do in a solution 

 as the results of the following series of experi- 

 ments show. 



Early in the spring of 1910 ten eight- 

 liter battery jars nearly full of solution con- 

 taining numerous didinia were set aside in 

 the laboratory. Eight of these jars were cov- 

 ered and two were left uncovered. The solu- 

 tion of one of these contained much debris, 

 hay, etc., that of the other almost none. The 

 solution in both evaporated gradually, so 

 that on the last day of May there was only a 

 trace of moisture left in either jar. When 

 they were next examined early in August the 

 debris was so dry that it could be readily 

 crumbled between the fingers. 



On January 14, 1911, one half of the solu- 

 tion in each of the eight jars was poured off 

 and replaced by hay solution (1 gm. hay to 

 200 c.c. water boiled ten minutes), and the 

 two empty jars were half filled with the same 

 solution. All of the jars were then examined 

 from time to time until February 10. Active 

 didinia were found in only one of the jars, 

 and this was one of the open jars, the one 

 which contained much debris. Several active 

 didinia were found in this jar January lY and 

 more later. Numerous colorless flagellates, 

 some vorticellse and also a few other forms 

 appeared but no paramecia. 



The results of these experiments, con- 

 sequently, clearly indicate that the vitality of 

 dried cysts is greater than that of wet cysts. 

 The nmnber of cultures tested was, however, 

 so small that the siginficance of the results 

 obtained is somewhat doubtful. The tests 

 should be repeated and extended in connec- 

 tion with a study of the histological changes 

 that may occur in the cysts. 



S. 0. Mast 



The Johns Hopkins TJniversitt 



SOCIETIES AND ACADEMIES 

 THE BOTANICAL SOCIETY OF WASHINGTON 



The 121st regular meeting of the Botanical So- 

 ciety of Washington was held in the Assembly 

 Hall of the Cosmos Club at 8 P.M., May 1, 1917, 

 with thirty-nine members present. Mr. Burt A. 

 Eudolph, Mr. Glenn C. Hahn and Mr. Horace W. 

 Truesdell were elected to membership. 



The regular program was devoted to a sym- 

 posium on the flora of the District of Columbia. 

 Professor A. 8. Hitchcock discussed "The plan of 

 the flora" and traced briefly the history of the 

 flora from Brereton's studies in 1831 to the pres- 

 ent time. In 1906 a. mimeograph list of the vas- 

 cular plants was prepared by Mr. P. L. Eicker. 

 The flora is now under the leadership of Professor 

 A. S. Hitchcock and Mr. P. C. Staudley. Twenty- 

 five collaborators are now at work preparing the 

 preliminary manuscript which is to be finished by 

 June 1 and the manuscript completed by November 

 1, 1917. 



Mr. Edgar T. Wherry, at the invitation of the 

 society, furnished a paper on "Geological areas 

 about Washington." The paper was read by Mr. 

 Hitchcock. The prominent geological feature is 

 the Pall Line which separates the Piedmont 

 Plateau on the northwest from the Coastal Plain 

 on the southeast. Above this line the valleys are 

 steep-sided, and below broad and open. The Pied- 

 mont Plateau consists chiefly of crystalline gneisses 

 of early periods, while the Coastal Plain is occu- 

 pied by unconsolidated gravels, sands and clays. 

 The soils on the Coastal Plain are acid for the 

 most part while those on the Piedmont are not. 



Mr. George E. Sudworth discussed "The distri- 

 bution of trees in the floral area. ' ' Oaks predomi- 

 nate and constitute from one half to three fourths 

 of the upland cover. There are about 140 species 

 of native and naturalized trees of which the broad- 

 leaved trees number about 122 species. 



' ' Humus as a factor in plant distribution ' ' was 

 discussed by Mr. Frederick V. Coville. Mr. CoviUe 

 exhibited two samples of organic matter — the one 

 a raw, brown and leafy turf found in laurel thick- 

 ets produced chiefly by the decay of the laurel 

 leaves, and the other a black, fully-reduced, non- 

 structural leafmold formed by leaves high in lime 

 content such as the tulip poplar. The former is 

 acid and the latter alkaline in reaction. 



Mr. P. L. Eicker discussed briefly the subject of 

 ' ' Collecting and preparing specimens. ' ' Mr. 

 Eicker exhibited several types of portfolios suitable 

 for collecting plants and also suggested the use of 

 corrugated driers and artificial heat, especially 

 where large numbers of plants are being collected 

 on field trips. 



The program was followed by an informal dis- 

 cussion by Messrs. Safford, Beattie, Norton, Waite, 

 Lewton, Shantz, Coville, Hitchcock, Sudworth and 

 Eicker. 



H. L. Shantz, 

 Corresponding Secretary 



