Febeuaey 5, 1909] 



SCIENCE 



237 



Male Female Male Female 



Producers Producers Producers Producers 



120 1 229 



23 8 390 14 



331 105 185 



32 1 127 



106 2 219 29 



152 177 209 9 



291 328 



240 3 386 



323 3 



ease only female producers. When it is re- 

 called that all the descendants can be traced 

 to a single egg fertilized by a " female-pro- 

 ducing " sperm the results are significant. It 

 is obvious that while the sex of the fertilized 

 egg is connected with the " female-producing " 

 sperm, the subsequent progeny may be either 

 males or females or a mixture of both. 

 Either external conditions determine the re- 

 sult (for which there is no evidence), or else 

 there is a strong "prepotency" of the egg or 

 sperm in one or the other direction. 



When it is recalled that the division into 

 male layers and female layers takes place one 

 generation prior to the formation of the sexes, 

 it will be manifest that the conditions that 

 determine the proportion of males and fe- 

 males, i. e., sex-determining factors, are to be 

 sought in a mechanism that lies behind the 

 one that excludes two chromosomes from the 

 male egg. 



Equally important is the fact that in the 

 latter process of elimination the result is not 

 haphazard, for the eliminated chromosomes 

 always pass into the polar body of the male 

 egg. Since we can identify this egg before 

 the elimination, we know that we are dealing 

 here also with an ordered series of events, and 

 not with an accidental shifting of chromo- 

 somes into one or another cell. 



T. H. Morgan 



COLXJMBIA UnIVEESITT 



MOMENTUM EFFECTS IN ELECTRIC DISCHARGE 



In Science of July 17 and December 4, the 

 writer has given some account of experi- 

 ments which seem to indicate momentum 

 effects, in electrical discharges around a right 

 angle in a wire. One interesting feature of 



the work was the formation of shadow pic- 

 tures of thin glass slides upon which lines 

 had been scratched. At the Baltimore meet- 

 ing of the American Association for the 

 Advancement of Science, a series of these 

 pictures was shown, some of which were of 

 special interest. 



A sheet of hard rubber one sixteenth of an 

 inch in thickness was pierced with a large 

 number of holes of various diameters. This 

 sheet was laid upon the photographic film 

 within a hard rubber holder. The wire angle 

 from which the fogging effects came was just 

 above the cover, and about 5 mm. from the 

 film. The holder rested upon a sheet of glass, 

 2 or 3 cm below, which was a grounded metal 

 plate. The film was more strongly fogged 

 at the bases of the larger holes than at those 

 of the smaller ones. The electrons were ap- 

 parently deflected to the sides of the smaller 

 holes to such an extent that few of them 

 reached the film at the bottom. Holes directly 

 below the wire gave images with sharp out- 

 line. Those to one side gave images having 

 on the sides remote from the wire diverging 

 lines indicating the repulsion of the accumu- 

 lating electrons on the film by the wire above, 

 and their repulsion for each other. The com- 

 parison of such shadow images with those 

 made by light shining through the same 

 holes showed differences of a very marked 

 character. 



Another interesting shadow picture made 

 just before leaving home, was produced by re- 

 placing the pierced rubber plate by small 

 fibers of glass, laid on the film at right angles 

 to the wire above. These fibers were about 

 half a millimeter in diameter. Some of them 

 were hollow tubes and some were solid. The 

 tubes gave shadows of uniform density. The 

 solid fibers showed conclusive evidence of re- 

 fraction. In every case the shadow image 

 shows a sharp black line along its center, 

 where the fiber made contact with the film. 



Wood, of Johns Hopkins University, sug- 

 gested that this might indicate the presence 

 of high frequency ether waves, and suggested 

 the use of red or yellow glass, with the other 

 glass fibers. 



