4H SCIENCE PROGRESS 



persisted in the interval between them. We may not know, 

 and may not be able to conjecture, the nature of this under- 

 lying cause or condition, but it is impossible to help postulating 

 its existence ; and with this causal basis the manifestations are 

 correlated : by it they are unified and constituted into a single 

 thing — a disease. In the third place, if this basis is postulated 

 to account for repetitions of a symptom, separated from one 

 another by intervals, equally is it postulated when there are 

 no intervals, and the manifestation or symptom is continuously 

 present ; or when, as in the case of a fatal first attack of angina 

 pectoris, it cannot be repeated. Whenever we speak or think 

 of a disease, we correlate what we observe with an intra- 

 corporeal cause, known, conjectured, or postulated ; and it is 

 this correlated group that constitutes the disease. 



For consider. Some disorders of function, both extrinsic 

 and intrinsic, are their own symptoms. We witness the dis- 

 order, or the immediate result of the disorder. Vomiting, 

 coughing, excessive or defective sweating are extrinsic disorders 

 of this kind : rashes on the skin and caries of the teeth are 

 results of disorder of intrinsic function. Are these disorders 

 diseases, or are they symptoms merely ? That depends 

 entirely on whether they do or do not enter as correlatives 

 into a combination of disorders all owning but one intra- 

 corporeal cause. Haematemesis and coughing are now known 

 to be correlated with other disorders — with disorder of the 

 intrinsic function of the stomach and structural lesion of the 

 stomach in the one case, and with some disorder of the air- 

 passages or lungs in the other. Haematemesis and coughing 

 are therefore now reduced in rank, from diseases to symptoms. 

 When they were diseases, they were correlated with a postu- 

 lated but unassignable cause, and were not contemplated 

 apart from that cause. Now that the cause is assignable, 

 they can be disentangled from it and contemplated apart 

 from it and isolated from it ; and so contemplated in isolation 

 they are no longer diseases : they are symptoms. If a rash 

 on the skin cannot be correlated with any other disorder, but 

 only with a cause, known or unknown, it is a disease, and is 

 called the disease of psoriasis, or acne, or icthyosis ; but if it 

 can be correlated with other disorders, such as fever, then the 

 rash is a symptom only, and the disease is the group, con- 

 sisting of the rash and the fever, correlated by some under- 



