MORPHOLOGY OF THE IDIOPLASM. 13 



Accordingly, each strand of idioplasm contains all 

 the determinants that the particular individual has 

 inherited in the germ cell, and each cell of the 

 organism is idioplasmatically qualified to become 

 the germ cell of a new individual. Whether this 

 qualification may be realized depends upon the 

 nature of the soma-plasm. In the lower plants this 

 power belongs to each individual cell ; in the higher 

 plants many cells have lost it ; in the animal king- 

 dom it is possessed in general only by cells nor- 

 mally set apart as asexual or sexual reproductive 

 cells. 



The continued phylogenetic formation of the 

 threads of idioplasm takes place by growth in the 

 cross section, which contains the sum of all the 

 determinants and changes in general only when new 

 rows of micellae are intercalated. But the rows of 

 micellae of the idioplasm join closely to each other, 

 according to their thickness, so that only rarely new 

 rows can enter, and then only at those definite 

 places where the cohesion is less strong and hence 

 is overcome. The cohesion varies irregularly because 

 the configuration of the cross section, conformably 

 to its origin, is never regular ; the disruptive ten- 

 sions are brought about by the unequal growth in 



nd movement," nor does he give a convincing explanation of the known 

 phenomena as results of the action of dynamic influence. 



Nageli is not the only one who posits dynamic rather than material 

 differences as to the basis of diversities of structure. More recently, Cope 

 has built up a system of evolution founded largely on this idea. TVanx 



