115 



will always be dangerous as the virulence of disease is not everywhere 

 the same and it is possible that an animal may be immunised against 

 the organism of one country and not that of another, and animals 

 having a latent infection are more susceptible to adverse conditions. 

 The destruction of ticks also makes the introduction of European 

 cattle possible, whereas under existing conditions such introduction 

 is difficult. If however such imported cattle could, on their arrival 

 in Africa, be at once distributed to regions where there are no ticks 

 and no trypanosomiasis, they could hve and breed as in Europe. 



The author quotes a case from the Transvaal in which 20 Hereford 

 cattle were imported from England direct, 3 years ago, and have done 

 exceedingly well ; the only precaution taken being rigorous protection 

 against ticks. He concludes with an earnest appeal to all cattle-raisers 

 to support universal dipping. 



SwELLENGREBEL (N. H.) & Otten (L.). Ueber '• mitigierte " Pest- 

 infektion bei Ratten und Meerschweinchen. [On 'mitigated" 

 plague infection in rats and guinea-pigs.] — Archiv fur Schiffs- und 

 Tropen-Hijgiene, Leipzig, xviii, no. 5, March 1914, pp. 149-159. 



In Java, rats and guinea-pigs were infected experimentally with 

 plague, and as a consequence showed the symptoms of a modified 

 form of the usual disease, which the authors call "mitigated" 

 plague. This form, which was transmitted by means of fleas 

 [Xenopsylla cheopis and Pygiopsylla ahalae), is characterised by the 

 length of time that the illness lasts, a month or more, and by various 

 pathological differences. The authors suggest that this form may be due 

 to the small quantity of virus which is injected, or to a partial immunity 

 of the infected animal, or to the bacilH being less virulent. This 

 " mitigated " form of the disease, especially when, as sometimes 

 happens, it takes on the characters of the acute form, is possibly to be 

 attributed to infection by rats from a distant locahty. The fact that 

 such a disease exists complicates the question of diagnosing plague 

 in rats on ships. 



Hadlington (J.). The Fowl Tick. — Agric. Gaz. N.S.W., Sydney, xxy, 

 pt. 4, April 1914, pp. 345-349, 2 figs. 



The author states that Argas persicus is one of the greatest handicaps 

 to poultry-keeping in some of the hot dry districts of New South Wales. 

 Many writers treat this pest as purely a blood-sucker, and all the trouble 

 to fowls is ascribed to this and to the irritation caused by the bites, 

 or to septicaemia. The deadly eft'ects of ticks are caused by a blood 

 parasite transmitted to the fowl inducing a fever which runs its course 

 in a few days, and is usually either immediately fatal, or leaves the 

 fowl so weak that it dies from anaemia ; if it survives it is immune to 

 further inoculations. 



The adult tick is rarely found upon the fowl except at night. During 

 the day it hides and lays its eggs in the cracks and crevices of the fowl- 

 house, fences, loose bark of trees, and any place where the fowls roost. 

 When the larval tick hatches, it attaches itself for a few days to the 

 parts of the fowl least covered with feathers ; it then drops oft", and 

 casts its skin ; this process is repeated, until and after the tick is 

 fullv adult. 



