'996 



SCIENCE. 



[N.S. Vol. XV. No. 390. 



of tlie plats is such that the currents of air 

 hugging the outside of the curve as they enter 

 the shaft will have a tendency from the west 

 wall toward the center. Moreover, it appears 

 that this tendency will be stronger close to 

 the wall than a little distance away. When 

 therefore on the 9th of January, the west 

 wire was moved eastward, lessening the dis- 

 tance between the lines, the wires hung more 

 nearly parallel than when this wire was close 

 to the wall of the shaft. 



It seems therefore that a very simple cause 

 was at the bottom of the divergence. The 

 remarkable fact is that the currents of air 

 should be so constant in their action. When, 

 however, the great depth of the shafts is con- 

 sidered, also the constancy for considerable 

 periods of time of the temperatures which may 

 influence these currents, it seems reasonable 

 that this steadiness should exist. 



F. W. MoNaie. 



Michigan College of Mines, 

 Houghton, Mich. 



sex in seed plants. 



PROBiiBLY everyone who has tried it will say 

 that it is not easy to teach students the rela- 

 tion between pteridophytes and seed plants. 

 Yet by following closely the origin of the spo- 

 rophyte and its gradual evolution the subject 

 can be made clear if all conditions are favor- 

 able. One important condition is that the 

 text-books consulted by the student shall be 

 perfectly clear, that there shall be no confu- 

 sion of terms. 



In popular accounts of plants, as in popular 

 works on science generally, one must expect to 

 find technical subjects treated in rather off- 

 hand fashion. But in works planned for col- 

 lege students it does not seem unreasonable to 

 ask for simple accuracy. Now it has long been 

 known that, among the seed plants, 'the plant' 

 is the sporophyte, a non-sexual organism. The 



stamens therefore cannot be male organs nor 

 the carpels female organs. Placing the pol- 

 len upon the stigma is not fertilization and 

 every botanist knows it. There are no such 

 things as male and female flowers, nor flowers 

 which are unisexual or hermaphrodite. 



Notwithstanding these well known facts, 

 many botanists continue to use these inaccu- 

 rate expressions. Practically all of the Euro- 

 pean botanical journals are serious offenders. 

 In our own country the first class journals use 

 the modern terminology but many of the most 

 widely used text-books do not. The most re- 

 cently issued American text-book, a work 

 intended for university students, contains the 

 misleading and irrational terms mentioned 

 above. 



Methods of teaching botany are frequently 

 discussed at educational conventions. To the 

 writer it seems that what we need is not some 

 new and fancy method of teaching but a 

 knowledge of facts by the teacher and an 

 ability to select a text-book which is clear and 

 accurate in its terminology — not muddled and 

 confused. Prancis Eamaley. 



Univeesitt of Coloeado. 



HARVARD COLLEGE OBSERVATORY 

 ASTRONOMICAL BULLETIN. 

 The determination of the law governing 

 the variation in light of the planet Eros (433) 

 is one of the most interesting problems in 

 Astronomical Photometry. A similar varia- 

 tion in light of the planets Sirona (116) and 

 Tercidina (345) has been announced by Dr. 

 M. Wolf, of Heidelberg. Both objects are 

 favorably situated for observation this sum- 

 mer. The opposition of Sirona occurs on 

 June 15, 1902, Magn. 10.9. Accordingly the 

 following ephemeris for Greenwich Midnight 

 has been computed by Mr. F. E. Seagrave, 

 of Providence, P. I., from the elements given 

 in the Berlin Jahrbuch for 1904. 



