Pathogenicity. Natural Infection. 149 



tion with colon bacilli, appears in smear preparations to be svirrounded by a broad 

 capsule. It grows only in alkaline media, especially well on blood agar, and also 

 in serum bouillon. 



The affection of the newborn of other species of domestic 

 animals is probably similar in its etiological relation. Thus 

 according to Hecker's investigations diarrhea in lambs is pro- 

 duced by the same bacteria as in calves, while Baldrey demon- 

 strated in white scours of a foal colon bacilli as the cause. 



Natural Infection. Sometimes the disease will appear in 

 localities which have previously been free from it, without 

 apparent introduction from the outside. In such cases it may 

 be assumed that the ordinary colon bacilli which have been 

 present in the stable, have for some reason attained virulent 

 properties in the intestines of the newly born animals (for 

 instance as a result of dietetic, errors, feeding of boiled milk 

 immediately after birth), and that this virulence is being 

 retained for later born animals. 



In affected stables the virus may be present in the vagina 

 of the mother, on the floor of the stable or in the litter, from 

 which the external genitals and the udder of the mother become 

 contaminated. The infection results usually during the sucking 

 of the contaminated udder, but also has taken place during 

 parturition, and later through contact with litter, from licking 

 of the stable walls, etc. Exceptionally the infection may also 

 take place through the umbilicus (Poels, Jensen). The affected 

 animals may then infect their surroundings with their excre- 

 ments and urine, thus increasing the possibilities for infection 

 of animals born later. Newborn animals fed artificially with 

 boiled milk may become infected by the contaminated hands 

 of the attendants as well as by the use of dirty feeding vessels. 

 In many instances the unfavorable experiences, gained in places 

 where animals are raised artificially (numerous affections with 

 diarrhea) may be attributed to a large extent to such infections, 

 but in such cases consideration should also be given to the fact 

 that by heating the milk substances are destroyed which are 

 valuable tor the digestion (ferments), which, if undisturbed, 

 counteract to some extent the development of diarrhea by stim- 

 ulating the function of the digestive glands, thereby preventing 

 the excessive multiplication of the normal intestinal bacteria. 



The contagion may retain its virulence in infected stables 

 for a long time, which may explain that in some premises where 

 nothing is done for the prevention of the disease it reappears 

 from year to year in the spring and in the fall. On the other 

 hand, the infective agent may be introduced into premises, as 

 yet free from disease, by infected sucklings as well as by adult 

 animals. The transmission of the disease by breeding animals 

 is especially suggested by the fact, that, where cows in advanced 

 pregnancy are taken from an infected stable and placed on 

 premises free from the disease, the calf born there is frequently 



