172 BOARD OF AGRICULTURE. 



phenomena may be considered in the light of incomplete 

 development, on accouut of the deficiency of primal force 

 which it is necessary for the germ to add to, through the 

 process of vitality, before sufficient force can be accumulated 

 for the production of the completed form. Thus the fern 

 sends forth a spore which is but an incomplete development 

 which obtains and elaborates its own nutriment, until it 

 accumulates sufficient force for the carrying forward of the 

 true generative act, which results in the formation of the 

 new fern. 



In so-called arrest of development, it is usually noticed that 

 the defect resembles the same part at an earlier period of 

 embryonic life, so that although growth may have continued, 

 yet it has not developed bej-ond the grade which it has already 

 attained in embryo. This is but another illustration of the 

 persistence of force ; the inherent power which influenced the 

 continued advancement of the part was deficient, and hence 

 there could be no progress. As the body is but the balance- 

 ment of all the forces which have taken part in its past 

 history, defects of a character which indicate cessation of 

 force are useful guides towards the study of the past history 

 of the race, or, in other words, the progress of evolution. 



It is, perhaps, the place to define what we mean by the 

 term "development." It is the word by which w T e express 

 the process through which a tissue or organ is formed, or by 

 which a tissue or organ or cell is changed so as to be fitted 

 for maintaining its relations with a more complex environ- 

 ment ; that is, fitted for a higher function. It is not growth 

 or mere increase ; it is the acquiring not of greater bulk, but 

 of new powers and structures which are adapted to higher 

 conditions of existence. The forces influencing development 

 and growth appear to be of a different intensity and charac- 

 ter, yet, under certain circumstances, seem mutually convert- 

 ible each into the other. 



Death is the limitation to the power of development. When 

 the demand upon a cell or a life is beyond the power of that 

 cell or life to respond, we find retarded development, or, as 

 it is generally called, disease, which must end fatally unless 

 the demands can be lessened or the power of the cell or life 

 increased. When the cells of the body have exhausted their 



