THE AGGLUTINATION TEST. 425 



whether a scrum is from a cow infected with the specific organ- 

 ism causing contagious abortion in cattle, and the sera of many 

 cows which do not abort give positive reactions even in dihitions 

 of 1:500 to 1:1000. On the other hand, though one cannot 

 predict an abortion, one can say definitely whether a cow which 

 has aborted was sufi:'ering from an infection with the organism 

 of contagious abortion or not, and even an isolated case of 

 premature calving in a clean herd should be sul)jected to the 

 test, as there is always the possibility of its being of a conta- 

 gious nature, particularly when the cow is a new purchase. As 

 the disease has already Ijeen introduced into Scjuth Africa, the 

 testing of all fresh cattle introduced into the country would not 

 be very much use now. Cattle which iiave recently aljorted are 

 the most dangerous as sources of infection, and it is a curious 

 fact that the serum of some cows will give a strongly positive 

 agglutination even two years after an aliortion, and in some 

 cases after having calved normally in the interval. Whether 

 such cows are a source of infection or not is a debatable ]joint 

 which is being put to the test, and should give interesting results. 

 Such cows must still have the organism in the body, as they 

 Avould not otherwise go on producing agglutinins. The eradica- 

 tion of the disease is more a problem for individual farmers than 

 for the State. A careful incjuiry into the history of any cow 

 bought by a farmer should always be made by him, and should 

 an abortion occur in his herd, the cow should be isolated imme- 

 diately, and the serum test applied, which it can always Ije, to 

 any serum sent in 1)}' a farmer lo a laboratory dealing with 

 diseases of stock. It should not ])e impossible to gradually rid 

 the country of this disease by a combined effort of farmers 

 with the aid of bacteriological institution- which undertake the 

 agglutination test for the disease, and to limit its spread from 

 farms at present infected should be rjuite a simple problem. 



Portland Cement. — In view of the stoppage of sup- 

 plies of L'ortland cement from dermany and Belgium, efforts are 

 being put forth to manufacture this article in other countries on a 

 large scale. \\'orks are being established at Darra, near Bris- 

 bane, to produce about 40,000 tons of cement j^er annum. Elec- 

 trically-driven grinding mills will l)e erected, the motors to be 

 three-])hase. 50 cycles of 440 volts. In this connection it is inter- 

 esting to note that the extensive gypsum deposits at Port NoUoth 

 have been accjuired by a Natal company, and are now in course of 

 transport to Pretoria for conversion into " Portland cement." 



