EVOLUTION OF THE COLORS OF BIRDS. 19 



cies of all the cells of the body form the efficient force for 

 the production of a new individual. This theory would 

 allow, nay, even necessitate, the inheritance of acquired 

 character. Prof. Ryder states this as follows: " Molecu- 

 lar impressions experienced in the course of variations 

 in the modes of manifestation of, or of disturbance of the 

 balance of the metabolism of the parent-body, are sup- 

 posed upon this view to be transmitted as molecular 

 tendencies to the idle or passive plasma of the germ- 

 cells. Variations in. the molecular constitution and 

 tendencies of the germinal matter are supposed to thus 

 arise at different times in the same parent, and that, 

 consequently, successive germs may be thus differently 

 impressed." 



The above view does not seem to be fundamentally 

 different from Haeckel's plastidule theory, although Ry- 

 der classes the latter with those from which his own is a 

 departure. The chief objection to it is its vagueness, 

 and it is to be hoped that Prof. Ryder may elaborate it 

 at some time. There ap-pears to be nothing expressed in 

 Lloyd Morgan's views contradictory to the theory above 

 stated. Morgan lays the greatest stress upon cellular 

 continuity. He regards ''the sharp distinction between 

 body-plasm and germ-plasm as an interesting biological 

 myth." He expresses his views on cellular continuity 

 as follows:* 



" The nucleus is the essence of the cell. And the doc- 

 trine of cellular continuity emphasizes the fact that the 

 nuclei of all the cells of the body are derived by a pro- 

 cess of divisional growth from the first segmentation 

 nucleus which results from the union of the nuclei of 

 the ovum and the sperm. In this sense, then, however 

 late the germinal cells appear as such, they are in direct 



* Animal Life and Intelligence, p. 142. 



