524 CHAPTER 67. 



1050. Of Home Specific Diseases. 



The Author believes that the germs of all home diseases are present 

 almost every-where, and Avill develop themselves wherever causes favor- 

 able for their development are present. Noxious weeds suited to the 

 climate are present almost everywhere, and will infest any garden or field 

 which is not kept clean by good horticulture or agriculture. So also the 

 germs of home diseases will develop and infest any house or stable which 

 is not kept clean and well ventilated. But noxious weeds, though indi- 

 genous to the soil and suitable to the climate, will not prevail where the 

 husbandly is good ; nor will the germs of specific diseases develop to any 

 great extent where pi'oper sanitary precautions are adopted. 



1051. Of the growth of Germs. 



What are the conditions necessary to produce development in the 

 germs of specific and contagious diseases? Seeds reproduce themselves 

 by germination in the earth. There is visible outgrowth. We do not 

 know, we cannot understand the processes of growth. But we can see 

 and easily recognise the result. 



In the few cases, in which germs of disease can be actually seen and 

 their growth watched under the microscope, it has been found that they 

 reproduce themselves in two ways — by division, the rod lengthening and 

 dividing into two — and endogenously by the formation of spores within 

 the cells, their development and growth being attended by various kinds 

 of fermentation. 



Yeast is probably the best known germ, the reproduction of which is 

 attended with fermentation. It will therefore serve well for the purpose 

 of illustration. We know the conditions necessary to cause the fermen- 

 tation and development of yeast. 



1st. There must be a nidus or soil suitable for its development, such 

 as dough. 



2nd. There must be warmth. 



3rd. There must be moisture. 



4th. There must be a confined atmosphere. 



If any one of these conditions is wanting, the yeast will not germinate, 

 or will do so imperfectly. It will be more or less inactive — the dough 

 will not be affected by it — the bread will be as " heavy as lead." 



Now the process of the growth or development of the germs of a 

 specific disease is much the same. Before the germs of disease will 

 develop in a house or stable, there must be a suitable nidus or seed bed. 

 There must also be a foul and confined atmosphere. The germs of disease 

 are generally of the nature of fungi. They thrive in a foul atmosphere. 

 They require warmth. They require a confined as well as a foul atmo- 

 sphere. Draught hinders their germination. A plentiful supply of fresh 

 air will after a time render their reproductive powers inert. 



1052. Where do Germs of Disease come from? 

 More or less it is probable that the germs of disease are present almost 

 everywhere in a dormant, i. e. undeveloped state. The foul confined 



