818 PRACTICE OF VETERINARY MEDICINE AND SURGERY. 
but many, if not all; may be earnest; patient, and enlightened 
workers in the field of observation; from which point we 
must ever consent to start in any true advance in pathological 
inquiry. 
In the exercise of this observation of morbid phenomena 
the signs and symptoms of disease; the agents or causes ope¬ 
rating in the production of the morbid conditions; and the 
associating of signs and causes, with certain disturbed or 
perverted functions or structural change, certain methods 
must be observed and means adopted to facilitate this 
observation and ensure its accuracy. 
Whatever may be the nature or extent of the significance 
which we may attach severally to the terms symptom and sign 
of disease, whether we regard these as simply every occur¬ 
rence or circumstance taking place or happening in the dis¬ 
eased animal which is capable of being perceived or appre¬ 
ciated, or as something in addition, as, in fact, a part of the 
disease itself, and as veritably a constituent of its existence 
and identity, as any specific lesion or structural change, we 
remember that, for the proper collection of these symptoms, 
appropriate means and methods must be employed, and that 
when possession of these is obtained much thought and 
reflection is needful for their correct interpretation. 
Symptom must be weighed against symptom, the relation 
of one to the other, and of the whole to each. Considered 
in this way only can we arrive at any just conclusion as to 
the nature of the disease, the probability of its course, and 
the termination of the treatment indicated. While as a 
means of systematising our knowledge as obtained by a 
study of symptoms or signs, and also of rendering it more 
definite, we agree to speak of these by terms to which, by 
general consent, a specific meaning is attached. 
Symptoms are general when they affect, to a greater or 
less extent, the whole system; local when confined to a par¬ 
ticular part or organ; premonitory or precursory when they 
precede the full appearance of the diseased action ; positive 
or direct when consisting of phenomena actually present; 
negative or indirect when such phenomena are absent; cha¬ 
racteristic when the same are usually seen in a similar 
disease; commemorative when developed during the course 
of the disease. 
They are also spoken of as diagnostic when they lead us 
to distinguish one disease from another; pathognomonic when 
peculiar to some particular disease; prognostic when they 
enable us to predict the course, &c., of the disease. 
In a similar way, and with like purposes in view, do we 
