
          The leaves in this put out around a stalk & would
 in ordinary plants assume a symmetrical position in
 reference to the stalk. But in this flowering Silphium laciniatum,
 they appear to take a medium position between
 its tendency to assume that symmetrical position 
 and its tendency to point north & south. All this
 I grant however requires more full & careful and repeated
 observation. Friends of mine, men of science
 at the most, learn from their observations not only confirmed
 the fact of the polarity of this plants, but say that they 
 find other plants exhibiting like peculiarities. This
 is worthy of investigation & may lead to some interesting
 generalizations. Dr. [Gideon?] B. Smith of Baltimore said
 that the Silphium terebinthinaceum had its leaves alternately
 east & west & north & south. 

 The cause of the phenomena is yet to be
 discovered. I still think that electrical currents will
 be found to be the cause, as it is well known in electric
 magnetism that there are many arrangements of [crossed out : the]
 such currents in our plane [added : moving in a vertical pivot] which would cause it to 
 point north & south; and certain other arrangements
 would make the plane [added : point] east & west.

 The resinous matter in the plant may be the cause
 but how remains to be set forth.

 I had general conferences in 1844 with your 
 friend Dr. Englemann [George Engelmann] of St. Louis. He promised to 
 endeavour to get time to observe it, but in '47 [1847]
 he wrote me that his professional labors had
 prevented his doing so.

 I have sent a paper going more at length into
 this whole matter to be submitted to the convention of the
 "American association for the Promotion of Science" which,
 it is announced, is to assemble at Cambridge Mass [Massachusetts] on the 14th
 August.

 I remain most truly & respectfully yours
 Benjn Alvord [Benjamin Alvord]
 Bt. Major U.S.A [United States of America]

 Prof.[Professor] John Torrey M. D. 
 Princeton N.J. 
        