Mat 2, 1913] 



SCIENCE 



673 



certain living plant organs, we will publish 

 the results of two series of experiments, one 

 on a 10 per cent, solution of lecithin in m- 

 kresol and the other on the leaf of Ficus elas- 

 ticus. In both experiments the E.M.F. at the 

 junction of these bodies and aqueous solutions 

 of various concentrations was measured. 



The differences observed for the same de- 

 gree of dilution are almost identical in both 

 cases and the drop in potential, if we substi- 

 tute m/10 HCl for to/10 KCl, corresponds for 

 a 10 per cent, lecithin solution to the change 

 observed in the case of the intact apple or leaf 

 of Ficus elasticus under the same condition. 



We obtained similar effects with chemically 

 pure kephalin which Dr. Levene was kind 

 enough to give us, and with triolein, oleic, 

 stearic and palmitic acids dissolved in guai- 

 acol or kresol. The kresol and the guaicol 

 without these lipoids gave concentration ef- 

 fects of a much smaller order of magnitude. 

 Cholesterin gave no concentration effects. 



We then made experiments with extracts of 

 the apple in guaiacol and this extract gave the 

 same results as the apple itself. 



We may therefore conclude that the concen- 

 tration effects on the E.M.F. observed in cer- 

 tain plant organs are due to the fact that 

 these organs possess a surface consisting of a 

 phosphatide or some fatty substance. It 

 would be wrong to conclude that the same is 

 true for the surfaces of all cells or organs. 

 In a number of organs, e. g., the striped 

 muscle, the concentration effects are extremly 

 small and it requires further experiments to 

 explain their electromotive behavior. 



Jacques Loeb 

 E. Beutnee 



The Rockefeller Institute 

 roR Medical Research, 

 April 15, 1913 



METEOR DUST AS A MEASURE OF GEOLOGIC TIME 



Some years ago' I suggested a possible 

 method of measuring the rate of formation 

 of strata, and so of geologic time, by the pro- 

 portion of meteor dust contained in the strata, 



* Annual report Michigan Geological Survey, 

 1901, p. 243. 



which method seems, now, to be really prac- 

 tical. Meteorites are continually striking the 

 earth. According to the Britannica, 20,000,- 

 000 visible meteorites strike the earth each 

 day and the telescope might reveal twenty 

 times as many. I then assumed that they 

 weighed a gram and were 10 per cent, nickel. 

 This would mean 28.6 grams of nickel per 

 square kilometer, per year. Professor W. H. 

 Pickering has shown reason to believe that 

 the visible meteorites are 15 to 18 cm., or, at 

 any rate, 5 to 7 cm. in diameter,^ and Far- 

 rington^ finds for the average specific weight 

 7.8 and for the average per cent, of iron and 

 nickel, in a large number of meteorites, 72.06 

 and 6.5, respectively. Assume that the in- 

 visible meteorites make up for any exaggera- 

 tion in Pickering's largest figure and that we 

 have 7,300,000,000 meteors, weighing 23,700 

 grams each, striking the earth in a year, and 

 we would have 340,000 grams per square kilo- 

 meter of cosmic material per annum, of which 

 20,000 grams are nickel. 



The .001 to .0001 grams per square meter 

 of partly cosmic dust found on a 30-milli- 

 meter layer of granular snow by A. E. Nord- 

 enskjold,* Lat. 80° N., Long. 15° E., might be 

 a small part of the year's accumulation. 



The redness of the residual red clay may be 

 due to the cosmic dust slowly added in this 

 slow process. This should also be a large 

 part of the abysmal red clay of the great 

 depths of the ocean. Of this red clay one 

 square kilometer, one meter thick, would 

 make 2,500,000 tons, if the specific gravity is 

 2.5. It contains, according to Clarke,' 0.0077 

 per cent, more of nickel than the average 

 igneous rock. Assuming the nickel of the 



' Astrophysical Journal, 1909, p. 378; 1910, p. 

 89. 



° Field Museum of Nat. Hist., Pub. 151, pp. 

 213-14. 



* Poggendorff's Annalen, Bd. 151 (1874), p. 

 158. See also ' ' Studien und Forschungen veran- 

 lasst . . . Norden, " von A. E. Nordenskjold, 

 Leipzig, 1885. Journal f. prakt. Chemie, N. F., 

 Bd. 9 (1874), pp. 356-67. 



" Data of Geochemistry, U. S. G. S. Bulletin 330, 

 pp. 490 and 27 (.0307 and .023). 



