526 CHAPTKR 67 A. 



they fijid a nidus may, and do, vary from day to day and from liour to 

 hour. 



1054. Conclusion — Specific Diseases. 



From the above it will be seen that though specific diseases are not of 

 spontaneous origin, yet they prevail mainly from causes which may fairly 

 be termed preventable, i. e. from neglect of good sanitary precautions. 



Specific diseases are generally regarded as infectious or contagious. 



But the prevalence and the virulence of these affections depend in a 

 great measure upon the sanitaiy arrangements of the house or stable. 

 Bad ventilation, bad drainage, improper and indifferent food and water, 

 want of cleanliness, etc., all tend to lower the system of man or animal, 

 and render it susceptible to the invasion and development of disease 

 germs ; while on the other hand, by the observance of due sanitary and 

 dietetic precautions, the tone, vigour, and general health of the body are 

 maintained, and the system is thus placed in the best possible condition 

 for resisting the influence of the contagium. No doubt specific diseases 

 may be and are propagated by infection or contagion. But such is more 

 rarely the case than is generally supposed. Similar causes produce similar 

 eft'ects, and are liable to produce disease among all the men or animals 

 subjected to their influence. It is but seldom that such diseases are 

 " caught," to use a conventional expression, from one man or animal to 

 another, if the sanitary arrangements in the house or stable are good. 



1055. Origin of Non-Specific, otherivise termed Spontaneous Diseases. 



Non-specific, other^vase termed spontaneous diseases, are those which 

 cannot be transferred from one living subject to another by inoculation 

 or infection, such as coughs, colds, fevers, affections of the lungs, liver, 

 kidneys, and stomach. There may be, and often is, great similarity in 

 cases of spontancou.^ growth, but there is no absolute identity as in 

 specific diseases. 



It is generally admitted that such diseases arise from causes peculiar 

 to the individual affected. They are generally due to bad stable manage- 

 ment, such as want of ventilation, bad food, over-feeding, want of exer- 

 cise, and neglect in grooming, especially in allowing a horse, when wet 

 or heated, to stand in the stable without being cleaned and dried. All 

 such causes produce ill-health, and so-called spontaneous diseases. 



CHAPTEE 67 a. 



BACTERIOLOGY. 

 1056. Science and the Microbe. 



Science, aided by the microscope, has within recent years opened to 

 us the knowledge of a numerous class of very minute creatures called 

 Germs, Microbes, or Bacteria, which belong to the vegetable kingdom, 

 and are at the very bottom of the scale among Living things. For all 

 practical purposes, these three may be classed under the same head. 



