MODE OF SPREAD OF INFECTIVE DISEASES. 737 



(ft) With greater resisting power (also transmissible 

 by various objects). 



The acute exanthemata (small-pox, scarlatina, measles, 

 &c.) : typhus fever. Sources of infection, the morbid pro- 

 ducts of the skin and mucous membranes. The ex- 

 citing agents are probably cast off in large quantities ; 

 they can withstand drying, they adhere to rags, wash 

 linen, beds, furniture, &c. 



Diphtheria : the sputa, membranes expelled by 

 coughing, secretions of the mouth, secretions from 

 other mucous membranes attacked by the disease. 

 The pathogenic agents can probably retain their vitality 

 in the dry state for a certain time, for how long is as 

 yet unknown ; they can adhere to the linen, bedding, 

 floors, soil, &c. We do not as yet possess more ac- 

 curate knowledge as to the nature of the sources of in- 

 fection. 



Tuberculosis : chiefly the sputa. The spores cast 

 off in the sputum retain their vitality in the dry state 

 for about six months. They can adhere to the linen, 

 clothes, furniture, &c. ; they are also present in tbe 

 soil under the flooring in a living condition, in the dust 

 of the streets, &c. In consequence of the large number 

 of phthisical patients, the number of the infective agents 

 in the sputa, and their resisting power, the sources of 

 infection are almost everywhere present. 



Glanders : the secretions of the diseased mucous 

 membranes, and of the ulcers of the skin, furnish the 

 infective agents in large quantities. According to 

 Loeffler's recent investigations spores are probably not 

 formed, for the dry cultivations usually die after some 

 days or weeks (it was only exceptionally that they were 

 found alive after three months), and a temperature of 

 55 C. kills the infective agents in five minutes. The 

 most important sources of infection are therefore the 

 fresh secretions and, for some days or weeks, the various 

 objects to which they adhere. According to Loeffler a 

 saprophytic growth of the bacilli does not occur in the 

 nutrient materials present in the stalls. 



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