lo Aug., 1912.] Tlic Etiology of Contagious Diseases. 489 



THE ETIOLOGY OF CONTAGIOUS DISEASES. 



TI'. .4. .V. Robertson^ B.V.Sc. 



(Paper read before the Farmers" Convention at Warrnambool. July, 1912^ 

 illustrated with lantern slides.) 



There is. unfortunately, a feeling amongst a large numf)er of the 

 farmers of this State that, though there may be something in germs, those 

 Government officers, \vho.se duties are somewhat inspectorial, are germ-mad, 

 and delight in imposing upon the farmers a lot of restrictions which, at 

 Hrst sight, appear unneoessary, and are a source of annoyance. This, in 

 many cases, leads to a desire on the part of those who are unfortunate 

 enough to be \isited by an outbreak of some contagious disease to keep 

 it as quiet as possible. 



It is hardly necessary to point out the folly of such an attitude, either 

 from the legal point — for it is a punishable oftence — or from the moral 

 aspect, and harm likely to follow in a district where certain restrictions 

 are not imposied. The subject of contagious diseases dealt with in a gene- 

 ral way would, therefore, not be out of place. Apart from the aspect 

 of controlling diseases existent in Australia is another, and, in many ways, 

 more important one, viz., the prevention of the introduction of disease 



(b) 



FIG. I. {a) STAPHVLOCOCCLS. [b) STREPTOCOCCUS. 



from other parts of the globe. What the result would be if the scourges 

 of India and Africa were introduced to this land it is hard to picture ; 

 for the introduction of a disea.se into a new land is always found a much 

 more severe affliction than in the land from which it came ; as exampled 

 by the terrible effect of Plcuro-fneumonia-contagiosa when it first appeared 

 in Australia. 



Later the causes of some of these diseases may. therefore, be lightly 

 touched upon. That they can only lightly be dealt with will be under- 

 stood when it is realized that each and every disease could by itself be 

 made ttie subject for a lecture, and some of them, indeed, the subject for 

 a series. 



That some considerable degree of confusion exists in the minds of 

 many as to a realization of the actual cause of disease must be admitted. 



Organisms or germs are bodies capable of life and death, and of pro- 

 ducing during their cycle poisons in the same way as our own bodies do, 

 and it is the poisons which are produced which are mainly the cause of the 

 sjmptoms we recognise in disease. They exist in many forms, all of 

 which are classified, and receive names indicating their forms, &c. The 

 most common forms are small round cellular bodies to which the name 

 of " Coccus " is applied. Thev mav be grouped in different manners, 

 as, for example, in clusters or in chains (Fig. i), singly, in pairs, fours, 



8805. i! 



