154 BOARD OF AGRICULTURE. 



proper to it when it was first formed, or in its .infantile life, 

 but with that which is proper according to the time of life in 

 which it is reproduced. In the reproduction of the foot or 

 the tail of the lizard, they grow, as it were, at once into the 

 full dimensions proper to the part, according to the age of 

 the individual. 



Each cell appears to be limited in its powers of w definite 

 expansion, and thus some connection is constantly preserved 

 between the early embryotic cell and the future progeny. 

 That is, as Paget well expresses it, the capacity of assuming 

 the specific organic form cannot be communicated to an indefi- 

 nite quantity of matter, for undoubtedly there is a consump- 

 tion of power in each organization of new matter, and in the 

 growth and maintenance of those parts already formed. We 

 have thus in the primal force a natural limitation. This repro- 

 ductive force appears stronger in the young than in the old, 

 and it would, therefore, seem as if the formative power is 

 more diminished by growth than by mere maintenance. But 

 again, as our author observes, the capacity for the repair or 

 reproduction of injured parts is much more diminished by 

 development than by growth or maintenance of the body ; 

 that is, much more by those transformations of parts by which 

 they become fitted for higher offices, than by the multiplica- 

 tion or maintenance of those that are already perfect in their 

 kind and function. In other words, to improve a part requires 

 more and more perfect formative power than to increase it 

 does. 



Changes may originate in a cell from cessation of force. — 

 If the cessation be final, we have destruction of form, or, as 

 we say, dead matter. If partial, an incompleteness, or a 

 check to the development of the new cell may result. 

 The forces which originate a cell, and which are contained 

 within the new cell, appear to principally affect the devel- 

 opment, while growth is largely from forces derived through 

 nutrition. This law of cessation of force oftentimes obscures 

 the presentation of other laws, especially the laws of sim- 

 ilarity. 



The cell is an entity, containing within itself its peculiar 

 forces, derived through inheritance and from its environment. 

 The forces must be derived from somewhere, for energy can- 



