214 From Matter' to Man. 



during the process of invagination, a central layer of 

 cells has been growing between the outer and inner 

 layers, called the mesoblast. The significant organic 

 facts in connection with these layers are that from the 

 epiblast are developed the permanent epidermis and 

 the outgrowths, the nervous system, and the organs of 

 sense ; from the hypoblast — the alimentary canal, 

 liver, pancreas, etc.; and from the mesoblast — the 

 bones, muscles, heart, blood-vessels, lymphatics, etc. 



From the gastrula stage a marked differentiation 

 begins, and the hidden constitutional features of each 

 organism become more and more developed until 

 such unlike creatures as fishes, birds, and beasts 

 diverge into their several classes, orders, and genera. 



(4) Animal Mechanism. — The animal mechanism 

 is dual. The one section works the body in all its 

 life processes, such as digestion, the circulation of the 

 blood, the action of the liver, kidneys, spleen, etc., and 

 does so unconsciously. The other connects the animal 

 with its externals through its sense organs, and does 

 so more or less consciously. But although dual, the 

 two mechanisms are so inter-related or inter-woven 

 that the growth or development of both from the 

 lowest animal to the highest proceeds contempo- 

 raneously. 



A protozoon's mechanism does not seem to be dual, 

 for it is apparently without sense organs, but in its 

 epidermis or whole external envelope it possesses an 

 organ practically comprising all the five senses. 



As a living magnetic machine, the chief mechanism 



