50 Causes and Course of Organic Evolution 



existed that must have been suited — even were requisite — for 

 such beginnings. 



Though only fragmentary indications of the pathway pur- 

 sued remain to us, these we beheve plainly show that colloid 

 molecules, of increasing complexity and diverse composition, 

 aggregated into equilibrated molecules of high mobility, but 

 extreme stability and tenacity of union. These, during trans- 

 ition from the inorganic to the organic state, differentiated 

 primarily in each mass into three inter-related lines of molec- 

 ular complexity. First into molecular aggregations which, by 

 long continued contact action and interaction, alike renewed 

 its o^Ti substance and effected upbuilding of diverse intrinsic 

 chemical products — both crystalloid and colloid — that together 

 constituted the substance protoplasm, and its accessory prod- 

 ucts. Second, other colloid aggregations arose that are now 

 identical with, or related to, nucleo-proteins, and which, by 

 analytic contact action, altered or split up elaborated colloids 

 and crystalloids, thereby setting free food products and ener- 

 gizing compounds for use of the organism. Third, that a 

 pigment slowly evolved from, but remained in contact with, 

 the protoplasm, which probably passed through successive 

 color changes and elaborating advances, from pale yellow or 

 yellow-purple through orange and orange-green to the stable 

 green substance chlorophyll, that is now a heritage of nearly 

 all higher plants. 



Such molecular aggregations would, from exposure for mil- 

 lions of years to varying and often rapidly changing environal 

 conditions of liquid tension and temperature, of gaseous dis- 

 charges, of liquid chemical stimulation and other modifications, 

 undergo very distinct and diverse modification as to shape, 

 size, consistence, and relation to surrounding media. So reac- 

 tion to such environal actions would give rise in the most 

 primitive cases to spherical mass-aggregations like Synecho- 

 cystis and Gloeocapsay or again into oval or elliptic bodies like 

 Aphanothece or Glceothece, or to such bodies in aggregate colloid 

 gelatinous masses as Aphanocapsa, to loosely united individuals 

 as in Onchobyrsa, or into elongate thread forms as in Beggiatoa, 

 Oscillatoria, Crenothrix^ etc. 



