72 HEREDITY. 



Excuse the shortness of the steps I take in the ele- 

 mentary stages of this argument. It is very neces- 

 sary, occasionally, in following out the links of a 

 course of thought, to use propositions that seem self- 

 evident. The strength of an argument is in the self- 

 evident propositions which it contains. Using often 

 here the form of statement which the logicians call a 

 catena, I shall be allowed, for the sake of brevity 

 and clearness, to develop argument by the use of 

 ordinal numbers for cardinal points. 



6. The co-ordinating force directing the movements 

 of germinal matter is defined as life. 



7. Life, therefore, is the cause of organization, and 

 not organization the cause of life. 



8. As the cause must go before the effect, life 

 exists and acts before the organization which it 

 causes. 



9. It exists and acts on a plan. 



10. In each different type of physical organism, it 

 exists and acts on a different plan. 



11. Every living being breeds true to its land. 

 We now approach wholly new matter in the shape 



of inferences from propositions already elaborately 

 discussed here. 



12. In the transmission of the co-ordinating force 

 called life, the force remains unchanged in the type 

 of its action. 



Of course I am not forgetting the slight exceptions 

 to this law, or variation in heredity ; but, to speak 

 roundly, the great rule of hereditary descent is that 

 like breeds like. 



