36 



pln'sical examination of the patient. Inspection and 

 comparison of one side of the chest with the other, 

 percnssion and noting the diflferent qualities of sound 

 produced thereby in different areas of the chest, the 

 alteration of the breath and voice sounds in its differ- 

 ing degrees as shewn on auscultation, and the varying 

 qualities of the thrill communicated to the palm of the 

 hand when laid on the chest while the patient repeats 

 the formula " ninety nine" — all these, together with 

 other observations which present themselves to the 

 skilled man, are absolutely necessary if one is to 

 diagnose such a comparatively simple thing as one of 

 the diseases mcTitioned. If then one or two mere 

 symptoms are of so little use in determining the cor- 

 rect nature of a disease in the human subject, what 

 can their value be in the case of a tiny bird in which 

 it is manifestly impossible to apply the extended tests 

 of physical examination? How caii we trust the 

 " expert's" diagnosis of asthma on the strength of a 

 bird's panting for breath? or how can we say with full 

 confidence that the same bird is suflfering from either 

 pneumonia or septic fever? Even in the same disease 

 the symptoms will be found to vary considerably in 

 individual cases, and this can be readily understood 

 when we once recognize that each symptom is but the 

 outward and visible result of some inward pathological 

 change, and therefore depends in a general way for 

 its own intensity upon that of the condition causing 

 it. And furthermore it will be equally clear that in 

 one and the same case any particular symptom may 

 vary from time to time. For instance, just as the 

 catarrh of the intestine (enteritis) is mild or severe, 

 so will the consequent diarrhoea be slight or profuse. 

 In like manner the character of the faeces will also 

 vary. They may be either glair}'' from the presence 

 of large quantities of mucus, or thin and frothy from 

 rapid decomposition while yet in the bowel ; either 

 pale in colour from retention of bile and its conse- 



