﻿Bones of the Skeleton as an Index of Nutrition, 207 



form of specialisation which makes little demands upon 

 protoplasmic activity. 



With regard to the second law of multiplication, it is 

 ouly necessary to point out that for cells individual 

 adaptation must mean specialisation which, by enabling the 

 cell to procure an increased supply of blood, or to exist 

 upon a diminished supply of blood, renders its environment 

 more favourable. 



The third law, " when favourable circumstances cause 

 any species to become unusually numerous, competition 

 becomes keener," is of importance, rather in connection 

 with the limitation of growth.^ Its meaning in terms of 

 metabolism is obvious. 



The fourth law, " individuation and genesis vary inversely," 

 with its corollary, " advancing specialisation must be accom- 

 panied by declining fertility," is at the root of the 

 phenomena of cytotnorphosis,^ for, histologically, it means 

 that it is useless to expect to find an active, fully developed, 

 highly specialised cell undergoing karyokinetic division. 

 This opens up a field for the study of the life history of 

 cells and of cell colonies. 



With these facts and theories fresh in our minds, we are 

 in a position to turn to an examination of the histology of 

 ossification. 



3. The Processes of Ossification in Terms of the 

 Theory of Growth. 



In order to avoid the appearance of consciously or un- 

 consciously distorting the facts to suit the hypothesis, I 

 propose to quote in full so much of a standard description 

 of the process as is germane to the point at issue. For 

 this purpose, I have selected the description of endochondral 



^ Cf. Roux Der Kampf der Teile irn Organismus, Leipsic, 1881. 



^ The word cytomorphosis was introduced by Minot in 1901, " to designate 

 comprehensively all the structural modifications which cells, or successive 

 generations of cells, undergo from the earliest undifterentiated stage to 

 their final destruction." 



