262 THE DISEASES AND DISORDERS OF THE OX. 



animals suflferiDg from cattle-plague. Semmer and Archangelski 

 have taken '* micrococci " from the lymphatic glands of a sheep 

 which had died as a result of having been inoculated with cattle- 

 plague, and succeeded in cultivating them in beef-broth and 

 other suitable fluids. The germs grew very copiously, and with 

 them a calf was inoculated. After seven days it died of cattle- 

 plague. 



Now if these micrococci are cultivated so as to give rise to 

 new generations, these germs are less potent for mischief in 

 proportion to the length of time and the number of generations.. 

 In other words they, in so far as they become accustomed to live 

 outside living animals, and hence under different conditions,, 

 become apparently less and less able to cope with the resisting 

 power possessed by the living cells contained in animals ; that 

 is, they cannot so easily grow and multiply inside the fluids and 

 tissues of the higher animals. Further, if sheep are inoculated 

 with the micrococci of such later generations, they are apparently 

 protected against the virulent form of the disease. If the germa 

 are heated to a temperature of about 47 deg. C, they also lose 

 a great deal of their power, and sheep, inoculated with germs^ 

 attenuated by this means, are not liable to attacks of virulent 

 cattle-plague. Very low temperatures, such as that of about 

 — 20 deg. C, also destroy the activity of the micrococci of 

 cattle-plague. 



It is on facts of this order that the advisability of the 

 precaution of protective inoculation in certain outbreaks of 

 disease is advocated ; but our readers will see that if all thia 

 knowledge and these great results have already been gained,, 

 still more valuable information will be acquired in the not 

 distant future. There is room in these days for many more 

 specialists on germs, for many workers who, being provided with 

 means, can afford to study under the few first-class workers in 

 England and on the Continent. Unfortunately this is not a 

 field of research which promises ready returns, and even the 

 skilful must be prepared, before they begin, to exercise their 

 abilities, not for money, but for very love of the work for the 

 work's sake. 



Itis very difficult to recognise cattle-plague unless its presence- 

 is suspected. This is in part due to the fact that it varies 

 greatly in the type which it assumes. It is, however, of the 



