December 4, 1914] 



SCIENCE 



827 



the constriction in that region may be so in- 

 hibited as to cause the two daughter cells to 

 reunite into one spherical cell but the daughter 

 nuclei remain separate. 



As this paper is concerned only with intra- 

 nuclear structures I shall merely mention here 

 that the mitochondrial threads characteristic 

 of the orthopteran germ cell form the bound- 

 ary of the kinoplasmic mass and give it an ap- 

 pearance of being composed of threads. I 

 have been unable to ascertain the existence 

 of spindle fibers. The chromosomes ra&y 

 easily be pulled out of the equatorial plate 

 and give no evidence of being attached to 

 such fibers. When one chromosome is dis- 

 lodged from the equatorial plate the others 

 leave their places, and if left to themselves, 

 clump together into an irregular homogeneous 

 mass. 



A curious phenomenon connected with the 

 dissolution of the cells is the production of 

 long slender processes which radiate in every 

 direction from the surface of the cells. The 

 ends of the processes soon grow into rounded 

 knobs which gradually increase in size and 

 often break off in the form of droplets. These 

 droplets rapidly go into solution. Within half 

 an hour or so, however, the entire protoplasm 

 of the cell takes up water and swells. The 

 pseudopodia are then slowly retracted and 

 the cell rounds up and may remain so for a 

 long time. 



During the first stages of their formation 

 the pseudopodia occasionally perform irregular 

 oscillatory movements. Their formation is 

 similar to that of sea-urchin eggs when sub- 

 jected to the cytolytic action of diluted KCl 

 solution. Similar phenomena have been de- 

 scribed by Kite^ and Oliver' and Merk* in blood 

 cells. Chromosomes show the same phenomenon 

 when isolated in Ringer's fluid. In one case 

 which was very striking a ring chromosome 

 was removed from the equatorial plate. Within 

 two minutes a pseudopod began to appear from 



2 G. L. Kite, ' ' Some Structural Transformations 

 of the BloodceUs of Vertebrates," J. Inf. Diseases, 

 XV., p. 319, 1914. 



3 Science, N. S., XL., p. 645, 1914. 

 iArch. f. Mihr. Anat., 80, 1912. 



one side of the ring. Within five minutes this 

 had lengthened into an attenuated filament 

 which oscillated slowly. The attenuated tip 

 gradually resolved itself into a knob which 

 soon was pinched off in the form of a droplet. 

 By the time a second droplet was formed and 

 pinched off the chromosome itself began to 

 swell and rapidly went into solution. 



According to the foregoing experiments the 

 chromosome appears to be a highly viscous 

 and glutinous protoplasmic gel readily swell- 

 ing in water and possessing very much the 

 same physical properties as the cytoplasm of 

 the cell. 



Egbert Chambers, Jr. 



Universitt op Cincinnati, 

 October, 1914 



THE GEOLOGIC HISTORY OF LAKE LAHONTAN 



The basin of the great lake that once cov- 

 ered much of western Nevada has been classic 

 ground ever since the early geologists first 

 studied it. The shore lines which are to-day 

 practically as the receding waters left them, 

 the calcareous deposits about its basin, the 

 possibility of saline deposits of commercial im- 

 portance, have made the deciphering of its 

 history one of the goals of geologic endeavor. 

 King,^ believing all of the tufa was a pseudo- 

 morph after gay-lussite and witnessing the 

 formation of the latter in the Soda Lakes, be- 

 lieved that Lahontan had become as saline 

 through desiccation, had then fallen, deposit- 

 ing the tufa as gay-lussite, and that a second 

 flooding of the lake had caused it to overflow, 

 washing out the saline material and changing 

 the tufa to calcite. 



RusselP determined that Lahontan had 

 never had an outlet and thereby vitiated 

 King's hypothesis. Believing that the tufas 

 were a deposit from waters saturated with 

 calcium carbonate and taking his clue from 

 the Great Salt Lake, Eussell assumed that the 

 waters of Lake Lahontan must have been 

 equally saline, although much of his evidence 



1 King, Clarence, U. S. Geol. Expl. of the 40th 

 Par., Vol. 1, p. 522. 



2 Eussell, I. C, Monograph No. 11, U. S. Geo- 

 logical Survey, 1885. 



