148 



THE ORIGIN AND EVOLUTION OF LIFE 



The principle of individuality, namely, of separate develop- 

 ment and existence, which we have seen to be the prime char- 

 acteristic of the first chemical assemblage into an organism 

 (p. 68), also governs each of the character complexes, as ob- 

 served by the palaeontologist. In some vertebrates we observe 

 an infinity of similar character com- 

 plexes, evolving in an exactly similar 

 manner, as in the beautiful mark- 

 ings of the shell and the exquisite 



Fig. 37. Similarly Formed Characters in the Glvptodon. 



Shell pattern and tooth pattern of the Glvptodon, a heavily armored fossil armadillo 

 found in North and South America. The entire shell is covered with rosettes, composed 

 of small plates nearly uniform in design, similar to those in the very small section repre- 

 sented {A). The entire series of upper and lower teeth bear within a uniform "glyptic" 

 pattern, like that of the tooth shown here {B), to which the name Glyptodon refers. 



enamel pattern of the teeth of the heavily armored armadillo 

 known as the glyptodon (Fig. 37), in which respectively every 

 portion of the shell evolves similarly and every one of the 

 teeth evolves similarly, from which we might conclude that 

 there is an absence of separability or individuality in form 

 characters and that some homomorphic (similarly formative) 

 impulse is present in all characters of similar chromatin origin. 

 But such a rash conclusion is offset by the existence of other 



