QUESTIONS 395 



first those of streptococci, but at the end of the fourth day they appear 

 more vigorous, and the surface colonies partake more of the character- 

 istics of Staphylococcus albus, although the color is of a yellowish- 

 white character. 



The thermal death point of the organism was ascertained to be 

 five minutes' exposure to 55 C. for the vegetative form, fifteen 

 minutes at 100 C. for the spores. 



Agglutination tests of the serum of cattle and man with the Bacillus 

 lactimorbi did not furnish any uniform results. Some sera would 

 agglutinate some stems of bacilli in dilution of 1 to 50 or 200; others 

 would not be agglutinated, and some stems of the organism could 

 not be agglutinated by any sera. 



Jordan and Harris found the Bacillus lactimorbi, or an organism 

 not distinguishable from it by any of the tests applied, in the soil of 

 regions where milk sickness has never been known; they found it in 

 normal cow dung, on various grain and forage plants. 



Luckhardt isolated an identical organism from dried alfalfa from 

 Wisconsin, from the same material from Illinois and Indiana, and 

 from four weeds collected by Jordan and Harris in the Pecos Valley 

 in New Mexico, where they first studied the disease. Of six dogs 

 inoculated with cultures of these stems of bacilli obtained by Luck- 

 hardt, two showed in a slight degree the symptoms observed in milk 

 sickness. Luckhardt concludes from his work with the Bacillus 

 lactimorbi that it is remarkable that if this bacillus be the cause of 

 milk sickness it should have so wide a distribution in milk-sick and 

 non-milk-sick regions. It is also apparent that loss of virulence 

 occurs after a time in the races of the organisms isolated, and that no 

 feeding experiments have so far yielded uniformly any well-defined 

 pathologic picture of the disease. 



The animal experiments of Jordan and Harris have likewise 

 lacked uniformity and definiteness in their outcome. On the whole, 

 it cannot yet be considered as established that the Bacillus lactimorbi 

 is indeed the cause of trembles. Some of the results of the animal 

 experiments made with the blood of dead animals and with pure 

 cultures of the bacillus rather point to the possibility of an ultra- 

 microscopic virus. 



QUESTIONS. 



1. What other names have been given to milk sickness in cattle? 



2. Where has the disease been encountered? 



3. What are its most characteristic symptoms? 



4. Describe the pathologic changes found after death from this disease. 



5. Is the disease communicable to man, and how? 



6. Describe the morphology and staining properties of the Bacillus lactimorbi. 



7. Describe a culture on agar. 



8. How does the organism affect milk when grown in it? 



9. Describe its growth in gelatin. 



10. What is the thermal death point of the vegetative form and of the spores 

 of the organism? 



11. What has been the result of agglutination tests with the organism? 



12. Where has the Bacillus lactimorbi been found outside of the bodies of 

 animals dead from trembles? 



