508 ANNUAL REPOKT SMITHSONIAN INSTITUTION, 19l2, 



primitive form of life would spread, and would gradually people the 

 globe. The establishment of life being once effected, all forms of 

 organization follow under the inevitable laws of evolution. Ce n'est 

 que le 'premier pas qui coUte! 



We can trace in imagmation the segregation of a more highly 

 phosphorized portion of the primitive living matter, which we may 

 now consider to have become more akin to the protoplasm of organ- 

 isms with which we are familiar. This more phosphorized portion 

 might not for myriads of generations take the form of a definite 

 nucleus, but it would be composed of material having a composition 

 and qualities similar to those of the nucleus of a cell. Prominent 

 among these qualities is that of catalysis— the function of effecting 

 profound cliemical changes in other material in contact with it 

 without itself undergoing permanent change. This catalytic function 

 may have been exercised directly by the living substance or may have 

 been carried on through the agency of the enzymes already mentioned, 

 which are also of a colloid nature but of simpler constitution than 

 itself, and which differ from the catalytic agents employed by the 

 chemist in the fact that they produce their effects at a relatively 

 low temperature. In the course of evolution special enzymes would 

 become developed for adaptation to special conditions of life, and with 

 the appearance of these and other modifications a process of differ- 

 entiation of primitive living matter into indi\dduals with definite 

 specific characters gradually became established. We can conceive 

 of the production in this way from originally undifferentiated living 

 substance of simple differentiated organisms comparable to the 

 lowest forms of Protista. But how long it may have taken to arrive 

 at this stage we liave no means of ascertaining. To judge from the 

 evidence afforded by the evolution of higher organisms it would 

 seem that a vast period of time wouUl be necessary for even this 

 amount of organization to establish itself. 



FORMATION OF THE NUCLEATED CELL. 



The next important phase in the process of evolution would be the 

 segregation and molding of the diffused or irregularly aggregated 

 nuclear matter into a definite nucleus around which all the chemical 

 activity of the organism will in future be centered. Wliether this 

 change were due to a slow and gradual process of segregation or of 

 the nature of a jump, such as nature does occasionally make, the 

 result would be the advancement of the living organism to the con- 

 dition of a complete nucleated cell: a material advance not only in 

 organization but — still more important — in potentiality for future 

 development. Life is now embodied in the cell, and every living being 

 evolved from this will itself be either a cell or a cell aggregate. 

 Omnis cellula e celluld. 



