BIOLOGY: H. F. OSBORN 
7 
opposite charges possibly arriving in great jets from the sun. Further 
the charges might be communicated to our air from such jets followed 
by discharge into space beyond. 
A sudden upHft of a highly charged thin air layer itself in waves or 
ridges might easily disturb the normal potential distribution and pre- 
cipitate discharges from the crests. Atmospheric currents or dis- 
placements may cause such upHfts as when a colder stream strikes 
down under a warmer charged layer. 
A set of vertical streamers would deflect a compass needle on the 
earth's surface one way or the other depending on whether such streamers 
exist to the north or to the south of the position of the compass. Observa- 
tions seem to confirm this but more work is needed. The direction of 
the compass deflection would determine the direction of the virtual 
streamer currents to which the deflection was due. Aside from these 
and other considerations, the effort has, however, been to present in 
this communication a rational theory which will at least enable a prop- 
er conception of the actual space relations of the visible portions of an 
aurora in relation to the earth's surface to be obtained; and to place on 
record ideas which through many years of consideration by the author 
have seemingly received at each appearance of an aurora with streamers, 
repeated confirmation. 
While I have in former papers, as in ''Thoughts on Osmical Electric- 
ity," an address before the Franklin Institute of Pennsylvania (De- 
cember 19, 1893) and notably in an address on Atmospheric Electric- 
ity" delivered at Princeton University October 21, 1909, and published 
in Science, December 17, 1909, pp. 857 to 869, given a brief sketch of 
some of the views presented, particularly the outward direction of the 
streamers, later observations have served to provide cumulative evi- 
dence and extend their application. 
APPLICATION OF THE LAWS OF ACTION. REACTION AND INTER- 
ACTION IN LIFE EVOLUTION 
By Henry Fairfield Osborn 
AMERICAN MUSEUM OF NATURAL HISTORY. NEW YORK CITY 
Read before the Academy, November 13, 1916 
Since 1893 I have been working upon the interrelations of the various 
so-called factors of evolution and have published a series of studies 
of this subject. In 1908 I presented before the American Society of 
NaturaHsts an exposition of a law which I termed ''the law of the four 
inseparable factors of evolution," these factors being regarded as the 
