70 



SCIENCE. 



[N. S. Vol. XXIV. No. 624. 



where o> is the water content and \V is the 

 maximum moisture of (wet) adhesion, and 

 where also J. is a constant. If this law of 

 attraction is used, we can determine the gen- 

 eral equation of water-flow in one direction in 

 soils by considei'ing the attraction at two 

 points removed by the distance dx of length, 

 and taking into account the resistance of flow 

 due to viscosity. The equation is, by employ- 

 ing the generalized Ohm's law, 



Kdt) +'*d^=^- 



If the boundary conditions can be satisfied 

 the flow of moisture can be determined from 

 one part of a soil to another with regard to 

 time. 



The 622d meeting was held on November 

 10, 1906, Vice-president Bauer in the chair. 



Mr. A. L. Day presented some results of in- 

 vestigations on * Lime-Silica Mixtures ' made 

 at the Geophysical Laboratory, Considering 

 first the materials separately: silica is melted 

 with great difficulty and becomes very viscous ; 

 the first traces of melting appear about 1,600° 

 C. ; powdered quartz heated in the electric fur- 

 nace and cooled shows traces of crystallization 

 as tridymite about 1,000° ; lime melts to a 

 thin liquid in the arc and when reciystallized 

 is very insoluble in water. Mixtures of the 

 two were studied pyrometrically, chemically 

 and microscopically. As the percentage of 

 silica increased the melting point generally 

 rose, the graph showing two maximum points, 

 corresponding nearly to definite chemical com- 

 binations, separated by sharp minima not 

 much lower in temperature. 



Mr. J. F. Hayford gave an account of the 

 /Meeting at Budapest of the International 

 Geodetic Association ' in September, 1906. 

 (See Science, December 7.) 



Charles K. Wead, 



Secretary. 



THE TORREY BOTANICAL CLUB. 



The second stated fall meeting of the club 

 was held at the museum building of the New 

 York Botanical Garden on October 31, 1906, 

 at 3:30 p.m. In the absence of the president. 



Professor H. M. Richards presided. Twenty- 

 three persons were in attendance. 



Dr. Britton presented the matter of the 

 club's action in connection with the meeting 

 of the American Association for the Advance- 

 ment of Science, to be held in New York City, 

 December 27-31, The program of meetings 

 for the association week was read and motion 

 was made that a committee of five, including 

 the chairman of the meeting, be appointed by 

 the chair, with power, to arrange for a recep- 

 tion to visiting botanists in Schermerhorn 

 Hall, Columbia University, on the evening of 

 December 26. The motion was carried. The 

 personnel of the committee is as follows: Pro- 

 fessor H. M. Richards, Professor L. M. Under- 

 wood, Dr. H. H. Rusby, Mrs. E, G, Britton, 

 Dr. C. Stuart Gager. 



The following papers were presented: 



Bemarhs on the Formation of Aerial Tubers 



in Solanum tuberosum: Dr. C, Stuart 



Gager. 



A brief outline was first given of the steps 

 in the germination of the potato seed, up to 

 and including the growth of the primary rhi- 

 zomes, and the formation at their distal ends 

 of the first tubers. Reference was then made 

 to two recent publications in Torreya (6: 181 

 and 211, 1906), describing an anomalous for- 

 mation of a tuber of Solanum tuberosum, on 

 a sprout from a seed tuber, in daylight, and 

 briefly summarizing the pertinent literatvire. 



The specimen in question, with photograph, 

 was then exhibited, and possible causes of the 

 anomaly discussed, Prunet's researches {Rev. 

 gen. d. Boi. 5: 49. 1893) led him to the con- 

 clusion that, at maturity, the apical and basal 

 ends of the mature tuber are physiologically 

 different, due to a redistribution, after the 

 cessation of growth, of the reserve materials 

 stored in the tuber while it was forming. The 

 validity of this conclusion has never been 

 tested by other investigators, and it was 

 thought improbable that such a condition, 

 even if it existed in the seed tuber which bore 

 the anomaly, would enter as a causative factor. 



The specimen exhibited, and numerous other 

 recorded cases of the formation of tubers on 

 aerial branches, render very improbable the 



