JUSE 16, 1922] 



SCIENCE 



647 



Non-reduction takes place in some cells, as 

 already described in triploid plants", resulting 

 in 2 giant cells from each pollen-mother-cell 

 instead of the 4 pollen grains expected after 

 reduction. The pollen-mother-cells are about 

 half the volume of the pollen-mother-cells of 

 diploid Daturas. Apparently the giant cells 

 form the surviving pollen grains of the haploid. 

 Since they are half the size of mother-cells 

 from which they arise (or one quarter the size 

 of the mother-cells of diploids) they are equal 

 in size to normal pollen grains of diploids and 

 may be expected to function in the same 

 manner. 



Haploidy is the normal condition in gameto- 

 phytes of all plants and is a regular occur- 

 rence in the males of such insects as honey 

 bees, which, however, fail to undergo reduction 

 at the formation of gametes. It has been re- 

 ported as an occasional ijhenomenon in sporo- 

 phytes of ferns. 



A haploid plant in Datura is a genetic 

 novelty among flowering plants for two rea- 

 sons : first, it is a sporophyte and yet has the 

 somatic chromosome number characteristic of 

 the gametophyte of the species; and second, 

 the chrpmosomes while in monosomes, or sets 

 of one each, still undergo a process of reduc- 

 tion though without synaptic mates. 



A. F. Blakesleb 

 John Belling 

 M. E. Farnham 

 A. Dorothy Bergnee 

 Casnegie Station foe 

 Experimental Evolution 



THE MASS OF THE ELECTRON AT SLOW 

 VELOCITY 



All assumptions regarding the form of the 

 electron in motion, with the possible exception 

 of the Parsons magneton, lead to expressions 

 for the longitudinal and transverse masses such 

 that the mass of the electron at slow velocity 

 is a constant, mo, independent of the direction 

 in which the inertia test is applied. 



An experimental confirmation is being car- 

 ried out with an apparatus similar to that pre- 



- Belling, John, and A. F. Blakeslee : ' ' The 

 assortment of chromosomes in triploid Daturas. ' ' 

 In press for Amer. Nat. 



viously used by one of the authors' except that 

 the cold cathode is replaced by an incandescent 

 filament to assure the presence of all possible 

 velocities at the same time. 



If an electron beam accelerated by a given 

 discharge voltage emerges from a tube in the 

 anode into the region between two horizontal 

 metal plates forming an electrostatic field and 

 if the electrostatic field be produced by the 

 same voltage as the discharge, or a constant 

 fractional part of it, then the point where the 

 beam will strike the lower (positive) plate is 

 independent of the discharge voltage and hence 

 independent of the velocity of the electrons 

 provided the transverse and longitudinal 

 masses be equal. This will be the case for 

 velocities below 10,000 volts. 



Visual results show the position of the spot 

 on the phosphorescent screen deposited on the 

 lowei' metal plate to be independent of the 

 exciting voltage, thus confirming the equality 

 of the masses at slow velocity. The photo- 

 graphic record of spot position and a more 

 complete description will be given later. 



The method is equally applicable to electrons 



of high velocity. The experimental work of 



verifying the expressions for the transverse 



and longitudinal masses at high velocity is 



Ijeing continued. ^ „ ^ 



L. T. Jones 



H. 0. HOLTE 



THE HYDROGEN-ION CONCENTRATION OF 

 SOILS AS AFFECTED BY DRYINGi 



Much interest has been manifested of late 

 in the determination of the concentration of 

 hydrogen-ions in agricultural soils and in the 

 study and possible correlation of data thus 

 secured. It was my privilege to attend the 

 meetings of the American Chemical Society in 

 New York last fall and, in one of the sections, 

 to listen to a somewhat lengthy discussion of 

 the probable effect of drying and heating soils 

 on their Pjj values. The discussion was of 

 necessity largely a matter of opinion due to 

 the paucity of expeiimental data bearing 

 directly upon this phase of the subject. 



During the past few months, in connection 

 with research projects relating to the subjects 

 of acidity and aluminum toxicity in soils, the 



1 L. T. Jones : Phys. Rev., 8, p. .52, 1916. 

 1 Contribution 286 of the Station. 



