810 Instruction in Geological Investigation. [Sept 
far it lends itself to the interpretation of the phenomena obe 
served, and to test experimentally every line of thought which 
points in this direction.” ee 
From the above sketch I have attempted to show that the 
hypothesis of evolution may also apply to the chemistry of 
plant compounds, and that plant chemistry will be found, like 
any special study, to include many others. It is, however, ex- 
ceptional in its broad range, and the variety of its topics, like 
the variations of flower-species, may be cultivated to suit the 
taste of the investigator. © ; 
INSTRUCTION IN GEOLOGICAL INVESTIGATION. 
. BY WILLIAM MORRIS DAVIS. 
Revised from a paper read before the Association of American Naturalists in Phili- 
delphia, December, 1886. ; 
eho a in geological investigation is so new 4 depart 
ment of teaching that it is little assisted or hampered bye 
ditional methods, Its best materials are found in the wide ou 
door laboratory, and as all out-door laboratories are of their a 
local kind, every teacher is required to develop his own R 
of using them; and he must count this to his advantage, for 
prevents him from doing his own work in some other a g 
way. The personality of the teacher must appear here ame 
. where ; and it must be strongly flavored with the local 
that spring up around him in new crops every year, and w ny 
own methods of attacking them. Instruction in geologic de | 
_ vestigation at any one place cannot therefore hope to wea 
completeness that may be attained in physics or chemistry, 
experiments are made to order in-doors, limited oe : 
funds than by the place of the laboratory. Conseque™ 
of the first aims of the instructor, and of the student t00 
take a proper share in laying out his own course of wor” 
be to see that his geological studies are pursued under wos 
one teacher and in many more than one place. di int 
this need, and so strong do I feel the limitations that o 
it, that I shall not presume to talk up to the gener “shall 
gested by the committee in charge of our meeting, ber 
