EN V IRONIC FACTORS 419 



The relation of plants, and of all organisms to water, is, therefore, 

 a fundamental one, and it is to the determination of these and other 

 important environic relations that a large share of the attention of the 

 department of botanical research is directed. If this conception has 

 been properly formulated you will be prepared to receive without sur- 

 prise the statement that the Desert Laboratory as the principal instru- 

 ment of research of this department was not established primarily for 

 the purpose of making studies upon desert vegetation as such. 



There is no adequate foundation for a science devoted to the organ- 

 isms which live in arid regions. There is no more a desert botanical 

 science than there is a mountain astronomy. The physicist seeks and 

 selects a place for the operation of his instruments in which observa- 

 tions and experiments may be carried on to the best advantage. The 

 biologist takes one of his laboratories to the seashore and another to the 

 desert, because here in these places organisms carry on the various proc- 

 esses in tissues of diverse structure and at different rates, and extended 

 facilities for experimentation and widened angles of observation are 

 made possible. 



If to these statements as to the purpose and general scope of our re- 

 searches, a few words be added as to the view-point taken as to the con- 

 stitution of living matter itself, we may then profitably proceed to a dis- 

 cussion of the main thesis of the present paper. 



Protoplasm is characterized by the fact that it includes an enormous 

 number of compounds of carbon, oxygen and hydrogen, which sustain 

 comparatively simple (chemical) structural relations to each other and 

 most of which are highly unstable. These two features make possible 

 variety and complexity in the mechanical structure and composition of 

 the tissues of plants and animals, give opportunity for the occurrence of 

 a multiplicity of chemical transformations in metabolism, and render 

 all the functions of the organisms highly modifiable. 



Any sense of daze we may experience from a contemplation of the 

 number of things, or combinations in protoplasm, however, is not a log- 

 ical excuse for going into the haze of vitalistic notions upon which 

 much of the pedagogical practise and speculative writing in biological 

 science of the present time is based. Ten, or ten million, the com- 

 ponents of protoplasm act in accordance with a few fundamental physico- 

 chemical laws. Complexity of composition yields in importance to the 

 types of energy transformations displayed, and to the external expres- 

 sion of what are known as the biological activities as they may be modi- 

 fied by the environment. 



The plant may be profitably visualized as an upright cylinder of 

 watery gelatine surrounded by a semi-permeable tubular casing. The 

 lower extremity of this cylinder is ramified into roots which are in inti- 

 mate contact with moist soil-particles, so that the water in the body of 



