166 BOARD OF AGRICULTURE. 



which itself possesses, and which, through natural processes 

 of development, is segregated from the parent for the purpose 

 of the new individual. The parent, through the vital proc- 

 esses, continually renews and increases the original develop- 

 mental force through nutrition and other circumstances of 

 environment. The brood from this parent do likewise, each 

 individual for itself. Deprive this group of aphides of all 

 nutriment whatsoever, and how far could the developmental 

 forces continue? 



The germ and the sperm have many points in common, 

 and, as shown by the history of their development, are 

 undoubtedly but differentiated products of the same funda- 

 mental element — the cell. According to the law of persist- 

 ence of force, the creation of a new product cannot be a 

 forming from nothing, but a transference only of force or 

 forces, form or forms, already existing. The germ and the 

 sperm cannot contain an original germ-force which of itself is 

 sufficient for all futurity, for such a proposition is simply 

 inconceivable. The forces which the germ and the sperm 

 transmit can be what they have, no more nor less. 



The germ and the sperm, therefore, contain not the total 

 force and all the forces which are to act during the life of the 

 product, but they do possess the forces necessary to originate 

 the new being and influence the development in certain lines, 

 and the capacity of adding to these inherited forces according 

 as opportunity offers. When the forces are insufficient for 

 these purposes the product dies. When the operations ot 

 these forces are misdirected by circumstances, — that is, a con- 

 flict with other forces, or checked, or accumulated in one 

 direction, or neutralize each other either wholly or in part, — 

 changes ensue ; and it is this fact, this application of the law 

 of persistence or indestructibility, which explains evolution and 

 insures progress in the development of individuals and races. 

 The forces derived from heredity, and the effect of nutritive 

 forces on their development, have a dependent influence, not 

 only in the parent, but during the whole life of the germinal 

 product. 



GENERATION. 



In some of the lower organisms the egg may be sufficiently 

 organized to continue its development without the added force 



