214 ORIGIN AND NATURE OF LIFE 



be shown how these balanced relationships 

 and sympathetic chemical affinities of colloids 

 become intensified and individualized as the 

 complex cell colonies come into co-existence 

 in the same organic whole, or body of the 

 higher animal. 



It must not be supposed that all bacteria 

 exist only as parasites within the bodies of 

 man and the higher animals ; many perform 

 indispensable functions in restoring dead 

 organic matter back to inorganic forms, 

 others, more directly useful still, attach 

 themselves to the growing rootlets of the 

 plants which supply our food, and enable 

 these to take up nitrogenous nutrient matter 

 from the soil. Without such common life 

 or commensal existence, the growth of some 

 of our most valuable food plants would be 

 impossible. 



In the bacteria, there are large groups 

 distinguished by the form of the organism, 

 such as the rounded micro-cocci, which are 

 subdivided again according to whether they 

 grow singly, or in chains, or groups, into 

 mono-cocci, diplo-cocci, strepto-cocci, and 

 staphylo-cocci. Similarly, in the rod-like 

 forms of bacteria called bacilli, in which 

 the relative length and breadth, straightness 

 or curvature, presence or absence of motile 



