156 BIOLOGICAL LECTURES. 



ation of the liver cells conditions or effects the transformation of 

 these cells from the tubular to the lobular type, whereby the 

 lobule for purposes of best nutrition accommodates itself inti- 

 mately to the tubular blood-capillaries. 



All these fixed "constant modi operandi'' of organic for- 

 mative processes must be still further determined with respect 

 to their place and the time, direction, and extent of their par- 

 ticipation in the special structures of organisms, and with 

 respect to their mode of operating. 



In the first place we shall have to ascertain a great number 

 of such constant modi operandi, and all of these must then be 

 further decomposed into simpler and more widely distributed 

 complex components. In this undertaking it will probably be 

 frequently possible to disentangle a simple component from 

 among the complex components. 



The immediate result of this undertaking, as in every 

 analysis, will be complication instead of simplification, since 

 apparently simple processes will often be separated into two 

 or more components. The simplifying effect of the analysis 

 will only appear after it has been extended to many processes 

 with the result of repeatedly finding the same components. 



This simplifying effect is already apparent : all the extremely 

 diverse structures of multicellular organisms may be traced 

 back to the few 7nodi operandi of cell-growth, of cell-eva- 

 nescence (Zellenschwund), cell-division, cell-migration, active 

 cell-formation, cell-elimination, and the qualitative metamor- 

 phosis of cells ; certainly, in appearance at least, a very simple 

 derivation. But the infinitely more difficult problem remains 

 not only to ascertain the special role which each of these pro- 

 cesses performs in the individual structure, but also to decom- 

 pose these complex components themselves into more and more 

 subordinate components. 



And notwithstanding such apparent simplicity, the formative 

 causes in each higher aggregation of living units may differ in 

 part from the formative causes of a lower order, as, e.g., for- 

 mative modes which belong to the independently existing lower 

 units, such as the Protista, may be absent in the higher state 

 of aggregation from the corresponding units, viz., the cells of 



