834 



SCIENCE. 



[N. S. Vol. XIX. No. 491. 



worthy of note. Lick Observatory Bulletin 

 No. 54 gives elliptic elements computed by 

 Messrs. Ourtiss and Albreclit. The extraor- 

 dinarily small eccentricity (0.17733) together 

 with the major axis (log a = 0.31970) at once 

 suggests asteroidal orbits. In fact, so far as 

 size is concerned, the orbit is seen to lie be- 

 tween the orbits of Mars and Jupiter, the 

 comet's perihelion distance being slightly 

 greater than the aphelion distance of Mars. 

 It will also be noticed that the eccentricity is 

 less than that of Mercury's orbit, and, indeed, 

 less than the eccentricities of the orbits of 

 many of the minor planets, including Eros. 

 But the inclination, more than 126,° with 

 consequent retrograde motion, of course sharp- 

 ly distinguishes it from any known planetary 

 orbit. 



However disappointing the comet may be 

 in its physical appearance and characteristics, 

 it is to be hoped that a number of observa- 

 tions may be secured and a study of the orbit 

 made, with especial reference to the comet's 

 past and future relations to Mars and Jupiter 

 when in or near its line of nodes. 



Ellen Hates. 



Whitin Obseevatoet, 

 Wellesley, Mass., 

 May 4, 1904. 



SPECIAL ARTICLES. 

 THE WATER-SOLUBLE PLANT POOD OP SOILS.* 



Data were given showing the amount of 

 phosphoric acid removed by crops, particularly 

 wheat, at different stages of growth. In the 

 case of wheat it was shown that from one 

 square yard of soil 1,106 grams of dry matter, 

 containing 10.18 grams of phosphoric acid, 

 were secured. Does all of this come from 

 water soluble forms? Reference was made to 

 Hellriegel's exhaustive work, ghowing that 

 359 grams of water are required to produce 

 one gram of dry matter in the form of spring 

 wheat. It was found that the quantity of water 

 required to produce 1,106 grams of wheat 

 could dissolve only 1.9 grams of phosphoric 

 acid from the soil upon which the wheat was 



* Presented at the St. Louis (1903) meeting of 

 the Society for the Promotion of Agricultural 

 Science. 



grown. In determining the water soluble 

 phosphoric acid the quantities of soil and 

 water recommended by Whitney and Cameron 

 in Bulletin No. 22, Division of Soils, U. S. 

 Department of Agriculture, were used. The 

 soil was left in contact with the water for 

 fifteen days. 



It was shown that if all the water taken from 

 the soil was in the form of a saturated soil 

 solution by physical action alone only 1.9 

 grams could have been supplied out of a 

 total of 10.18 grams, in water-soluble forms. 

 The conclusion was reached that over 81 per 

 cent, of the phosphoric^ acid of the wheat crop 

 was secured from forms insoluble in water. 

 Similar data for oats, peas, corn and flax 

 showed that the water-soluble phosphoric acid 

 was only a minor factor in the food supply of 

 the crops. 



Some of the data in Bulletin No. 22 were 

 examined. The experiments by Birner and 

 Lucanus were reviewed, and it was shown that 

 all of the data were not given. Instead of 

 being a normal oat crop, as claimed by Whit- 

 ney and Cameron, it was shown that Birner 

 and Lucanus secured from three to six times 

 as much organic matter when more plant food 

 than that secured in the well water was sup- 

 plied. There were abnormal amounts of plant 

 food, particularly nitrates, in the well water; 

 over sixty parts per million were present. This 

 was shown to be more than is found in Lon- 

 don sewage. The work of Birner and Lucanus 

 can not be questioned, but the application of 

 their results was shown to be inconsistent. It 

 was noted on one page (10) that ' with the 

 chemical methods then available it was realized 

 that the small amount of plant food contained 

 in a soil extract could not be determined with 

 sufficient accuracy to justify the formation of 

 any definite conclusion,' and then on a subse- 

 quent page the results of Birner and Lucanus, 

 obtained in 1863-1866, by such methods, are 

 cited as the only evidence that plants obtain 

 all of their food from water-soluble forms. 



The action of plant roots upon limestone is 

 accounted for by Whitney and Cameron by 

 the soil water being charged with carbon 

 dioxide. It has been shown that the same re- 

 sult was secured when most seeds were germi- 



