THE CONSTITUTION OF MATTER. 21 



centre it thickens to produce the vitelline nucleus. This in 

 turn cleaves and breaks into a great number of secondary 

 nuclei, around each of which the ovular mass distributes 

 itself while contracting. Instead of a single cell, the ovule, 

 which has enlarged, is now found to contain a great num- 

 ber. These cells, called blastodermic, then tend to arrange 

 themselves hi two layers, two leaflets placed back to back, 

 within which the elements of the embryo appear, and little 

 by little develop, pursuing a continuous growth, in which 

 forces becoming forms go on incessantly producing and 

 multiplying new forces and new forms. 



Now, these separations and distributions, these order- 

 ings and classifyings, these harmonies that are set up in 

 the ovule to compose by slow degrees the structure of the 

 embryo, reveal a principle of differentiation analogous to 

 that which has caused the infinite variety of things we see 

 come forth from the confused mass of cosmic energies. 

 There is, as many biologists had felt assured, and as Coste 

 has had the glory of clearly demonstrating in a work which 

 is one of the noblest scientific monuments of this age, 

 there is a force which gives reality, direction, life, to the 

 forms of organized matter in the egg. All eggs are alike 

 at first. There is a complete similitude in structure and 

 substance between those which will produce a lion and 

 those which will produce a mouse. The forms are iden- 

 tical, though the futures of those forms differ. It is, as 

 Coste very well says, that " beneath that form, and beyond 

 what the eye views, there is something which sight cannot 

 reach, something which contains in itself the sufficient 

 reason for all those differences now concealed under unity 

 of configuration, and to become visible only later." This 

 guiding idea, which Coste has brought forward, and which 

 is admitted by all physiologists at this day, is as far from 

 issuing out of the elementary forces of nutrition as the 

 painter's picture is from being the creature of his palette. 



