Jxn.Y 28, 1905.] 



SCIENCE. 



119 



made up of a stream of particles 1/2000 the 

 size of those of the a-rays and carrying a 

 charge of negative electricity; (3) the y-rays, 

 analogous to X-rays, but much more pene- 

 trating; (4) the emanation, which in a proc- 

 ess of ' decay,' gives off a-rays as described, 

 and eventually the ^- and y-rays mentioned 

 above. The emanation behaves as a very 

 heavy gas and may be condensed on a solid 

 surface at a temperature of — 150° C. The 

 influence of radium upon plants, therefore, is 

 of the nature of radiant energy. 



The radium was employed in the foi'm of 

 the salt, radium bromide, of three strengths 

 of activity, 1,500,000, 10,000 and 7,000 en- 

 closed in sealed glass tubes, and also in the 

 form of celluloid rods and cylinders covered 

 with Lieber's radium coating of 10,000 and 

 25,000 activity. The glass shuts off prac- 

 tically all the a-rays, the (3-rsijs penetrate 

 through the glass more easily, while the y- 

 rays pass through glass very readily. By the 

 use of the coated rods and tubes all three 

 kinds of rays are available as well as the 

 emanation. 



The experiments indicate that the rays act 

 as a stimulus, which varies in intensity with 

 the strength and amount of radium used, the 

 thickness of the seed-coats, distance of ex- 

 posure and the intervention of moist soil be- 

 tween the radium and the plant. If the 

 stimulus ranges between a minimum and an 

 optimum germination and subsequent growth 

 are accelerated. Within these limits the rate 

 of alcoholic fermentation is at first increased, 

 but continued exposure may result in over- 

 stimulation and consequent decrease in rate. 



By over-stimulation germination and growth 

 of seeds, gemmae of Hepatica^, and pollen 

 grains are retarded and may be completely 

 inhibited. Under the influence of the rays 

 chloroplasts change their position in the cell, 

 as under too intense illumination, and they 

 are eventually destroyed, as is embryonic tis- 

 sue in stems and roots. 



Results similar in kind to the above are 

 obtained by the use of radio-tellurium in a 

 sealed glass tube. The influence here is con- 

 fined chiefly to the a-rays. Experiments with 



a rod coated with pollonium, which gives off 

 a-rays exclusively, have thus far given nega- 

 tive results. 



Growth is retarded and may be inhibited 

 by growing plants in an atmosphere contain- 

 ing the radium emanation, such as may be 

 drawn from a cylinder lined with Lieber's 

 coating. 



Photographs of the experiments and speci- 

 mens of the various radio-active preparations 

 were exhibited. 



The second paper, entitled ' Some Interest- 

 ing Plants from Colombia,' was by Dr. H. H. 

 Rusby. 



In view of the lateness of the hour Dr. 

 Eusby stated that he desired to reserve his 

 paper as planned for some future meeting, 

 when he could take the time to treat it more 

 adequately, and for the present he would show 

 some of the more interesting specimens and 

 briefly comment on the same. 



The collections were made by Herbert H. 

 Smith, who spent four years collecting in the 

 United States of Colombia near the town of 

 Santa Marta, which is about fifty miles from 

 the coast in the Sierra Nevada Mountains. 

 Although this territory was collected over 

 quite extensively by Karsten, whose collections 

 are at St. Petersburg and consequently not 

 readily accessible, and by Wm. Purdy, and 

 various orchid collectors, Mr. Smith's efforts 

 disclosed many novelties. 



The total collection studied contained about 

 3,000 numbers, embracing between 2,300 and 

 2,400 species, of which number about fifteen 

 per cent, are likely to prove new to science. 



The specimens exhibited were most interest- 

 ing, embracing arborescent Violacese, hand- 

 some twining Senecios, showy Vacciniacese, 

 numerous anomalous Compositse, and many 

 other things undreamt of by collectors in tem- 

 perate climes. Edward W. Berry, 



Secretary. 



DISCUSSION AND CORRESPONDENCE. 



EXOGLOSSUM EAST OF THE DELAWARE BASIN. 



■ To THE Editor of Science: In the issue of 

 June 30, last, Mr. H. W. Fowler, of Phila- 

 delphia, writes on the occurrence of Exoglos- 



