178 THE CAUSATION OF DISEASE. 



next our business to trace out the several secondary morbid 

 inter-actions — those, namely, due to secondary mal-E's — and to 

 place in its proper order each of the many links of the morbid 

 chain. 



It is very seldom that the method, as above set forth, can 

 be followed with any minuteness, for the- difficulties are many 

 and great ; these are, nevertheless, the lines on which our search 

 should be carried out. 



As regards the cjctcrncd-body-E, this is far more compli- 

 cated than at first sight appears. It may be classified as 

 follows : — 



T ~ . (a. Mental. 



[b. Physical. 

 II. Inorganic. 



The inorganic E refers to temperature, atmospheric conditions, 

 and so forth. The organic E embraces the relations of the 

 individual to the organic world, animal and vegetable. The 

 relations of man to the animal world are many and complex. 

 Those of man to man are very largely considered under 

 the science of Sociology and Ethics, but they also fall within 

 the province of the pathologist, for disease may be the out- 

 come of these relations. As regard the relations existing 

 between man and other animals, this is twofold — for first, our 

 food supply is largely derived from the animal kingdom ; and 

 secondly, we are brought into contact, offensive and defensive, 

 with many of the members of the animal kingdom, though in 

 civilized countries this only happens to a slight extent. 



Concerning our relation to the vegetable world, this like- 

 wise is twofold. (1) We are absolutely dependent upon it 

 for our existence, for not only is our food supply chiefly drawn 

 from the vegetable kingdom, but plants break up the C0 2 

 excreted by the animal world, and thus render animal life 

 possible. (2) We are brought into defensive contact with 

 myriads of unicellular organisms belonging, for the most part, 

 to the vegetable kingdom. Indeed, our struggle against these 

 is infinitely greater than that against the members of the 

 animal kingdom. 



