30 Causes and Course of Organic Evolution 



develops structures like those of living organisms, and it is 

 sensitive to many exterior changes, which influence its form 

 and development. But these very phenomena — nutrition, 

 assimilation, sensibility, growth, and organization — are gener- 

 ally asserted to be the sole characteristics of life." 



Nay more, under the conditions that must have pertained 

 during the early archsean epoch, such actions and reactions 

 must often have occurred, in presence of the considerable 

 colloid masses that must then have existed. But further the 

 fact deserves to be emphasized that the transition from a 

 crystalloid to a colloid body, or vice versa, is often rapid and 

 continuous, as already indicated for iron and silicon colloids. 

 Tliis is equally true for "organic" compounds. Thus the 

 crystalloid sugars can be changed quickly in plant cells into 

 the colloid starch. Cellulose and inuhn can be quickly trans- 

 formed into sugars. The amides and even the albumen com- 

 pounds can be resolved into crystalloid constituents. 



But such considerations would form a feeble means of ex- 

 plaining the formation of complex plant and animal proteids, 

 still less of protoplasm itself. We may, however, attempt to 

 analyze primitive plant structures and activities into their 

 apparently primary factors, so as thereby to reach the nearer 

 to inorganic relations. So when we study the structure and 

 life phenomena of such simple non-nucleate plants as Gloeo- 

 capsa and Chroococcus, apart from the colloid cellulose wall, 

 three fundamentally important but intimately cooperative 

 constituents are recognized. Firsts a colorless colloidal syn- 

 thetic protoplasm, which in virtue of its intra-molecular energy, 

 and the contact relation between the energized molecules, 

 can build up complex food substances into proteids allied to 

 itself; second^ a colorless metabolic colloidal constituent or 

 set of constituents which can transform or split up formed 

 foods into assimilable — and usually simpler — bodies, that are 

 then utilized by the protoplasm; third, a green substance, chloro- 

 jjhyll, which can absorb sunlight, and, by its energy in pres- 

 ence of the protoplasm, can link up simple inorganic constituents 

 — carbon and water — into the primary food constituents. 



