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NATURE STUDIES. 



death. So far, then, the parallel between ordinary 

 life and the birth, growth, and decline of a disease, is 

 very close and clear. 



But the analogies are not yet exhausted. Each 

 fever produces its like, as do animals and plants. 

 Each disease reproduces its kind, as Tyndall has 

 somewhere observed, 1 as rigorously as dog and cat 

 reproduce their like. The phenomena, or, as a doctor 

 would call them, the ' ' symptoms/' of each disease are* 

 as a rule, highly distinctive. The symptoms of scarla- 

 tina are not those of small-pox ; measles is different 

 from the other two ; whilst typhus fever is again 

 thoroughly different from all three. Analogy may, as . 

 Darwin says, be a deceitful guide ; but when the facts 

 are so closely allied, as are the facts of epidemic 

 diseases to those of animal and plant development, 

 the use of analogy cannot be doubted in rendering the 

 relationship clearer. 



We are now in a position to understand more clearly 

 the utility and strength of the germ theory in certain 

 of those aspects which bear most materially on science 

 at large. It would only serve to strengthen the idea 

 that our epidemic diseases are simply the offspring of 

 lower life, if we reflect in passing that there are 

 known to science a very considerable number of lower 

 plants which produce in man's skin effects and diseases 

 as characteristic as those which a fever induces in his 

 system at large. Thus, the disease known as " ring- 



1 Quoting a remark by Miss Nightingale. ED. 



