August 2, 1912] 



SCIENCE 



153 



SPECIAL ARTICLES 



A REVERSAL OF THE ROWLAND EFFECT 



The result of Eowland'a Berlin experiments 

 showed that a wire having a supercharge of 

 negative corpuscles, moved longitudinally in 

 a plus direction, and a wire having less than 

 a normal charge, moved in the opposite direc- 

 tion, would produce the same external field. 



In a paper just being issued by the Acad- 

 emy of Science, of St. Louis, the writer shows 

 that when this external field is imposed upon 

 a wire, the corpuscular column within the 

 wire, and the wire itseK, are moved in opposite 

 directions. 



A copper wire having a diameter of about 

 0.2 mm. and a length of 55 cm. is placed within 

 a horizontal glass tube of three or four mm. 

 diameter and 50 cm. in length. About 1.5 

 cm. of the wire at each end is bent at right 

 angles and hangs vertically. Spark knobs on 

 long rods connected with the terminals of an 

 eight plate influence machine, are placed di- 

 rectly over the ends of the tube. A condenser 

 of sheet glass having an area of tin-foil on 

 each side of 1,000 or more sq. cm. is connected 

 with the discharge rods. The spark length 

 was about 4 cm. at each terminal. Sparks 

 passed into the side of the wire at the ends 

 of the tube, at intervals of one to three sec- 

 onds, depending upon the length of the spark. 

 The machine was driven by a motor. The 

 end of the wire was observed by means of a 

 telescope magnifying about 27 diameters. 



No motion of the wire due to a single 

 spark can be observed, but after four or five 

 sparks have passed, one can easily see that it 

 has moved. 



The ends of the wire are slightly lifted as 

 the potential rises, and drop when the spark 

 passes. The entire wire is somewhat shaken 

 by the spark, and the effect is to somewhat 

 diminish friction. The interaction between 

 the ends of the wire and the surrounding air 

 is very slight, but it is directed at right angles 

 to the direction in which the wire creeps. 



In one case the effect of 3,500 sparks caused 

 the wire to creep over a distance of 1.2 cm. 



The paper contains other evidence that such 

 a solid conductor has the properties of the 

 positive column. In one case a i ampere fuse 

 wire in a tube filled with coal oil was fused by 

 a single spark, and became solid again at the 

 instant when it had buckled into a regular 

 series of longitudinal waves. In one case the 

 compression halves of the waves separated 

 into minute spheres, there being about a thou- 

 sand of them distributed quite uniformly 

 over a half meter of the tube. 



No creeping of the wire could be observed, 

 when the ends were dipped into mercury cups 

 and a separately excited dynamo having a ter- 

 minal potential of 175 volts was momentarily 

 connected with it. Such effects have been ob- 

 served when high potential discharges wholly 

 outside of the wire have passed between the 

 terminals of the influence machine. These ef- 

 fects have not yet received careful attention. 

 The action of the coherer is of this character. 



Feancis E. Nipher 



THE preparation OF UNBROKEN POLLEN MOTHER- 

 CELLS AND OTHER CELLS FOR STUDIES 

 IN mitosis' 



Some recent investigations in the study of 

 pollen mother-cells without the use of the 

 microtome have made it evident that there are 

 certain advantages in preparing and studying 

 unbroken cells for investigation in mitosis. 

 Those in the Bureau of Plant Industry who 

 have examined this method have suggested 

 that a short paper be presented to this society, 

 in order that other workers may try out this 

 method and cooperate in improving its technic. 

 The method seems to be capable of quite wide 

 application in karyokinetic study. 



The stamens of a large percentage of our 

 flowers yield the unbroken pollen mother-cells 

 with very little difliculty. Such plants as the 

 grasses, including our grains, supply an abun- 

 dance of material by simply placing the an- 

 thers in a drop of water, cutting the tips with 

 a sharp scalpel and gently tapping them with 



• Read before Section of Botany, American Asso- 

 ciation for the Advancement of Science, 1911 

 meeting, Baltimore, Md. 



