88 THE GROUSE DISEASE chap. 



the microscope, this condition, viz. the relative scarcity 

 of the bacteria in the blood, was confirmed (Fig. 41). 

 It was at the same time noticed that the bacteria were 

 distinctly thicker and longer than in fowl cholera, they 

 occurred also as single rods or as dumb-bells with 

 rounded ends. This condition, as regfards the bacilli 

 in the blood, was uniform in all the fowls that I got 

 from Orpington, as well as in those which were in- 

 fected in the laboratory from the Orpington fowls. 



Thus far it was quite clear from these observa- 

 tions that the Orpington disease differed from fowl 

 cholera: (i) in the absence of hsemorrhagic changes 

 so common in fowls dead of fowl cholera; (2) in 

 the scarcity of the bacteria in the blood ; (3) in the 

 difference in size between the bacteria present in 

 the blood of the Orpington fowls and those of the 

 typical fowl cholera. Further differences established 

 were these : the spleen of the Orpington fowls, 

 examined in cover-glass specimens, contained the 

 bacteria somewhat more numerously than the blood 

 (Fig. 42), but very far less numerously than in fowl 

 cholera, and also the bacteria of the spleen of the 

 Orpington fowls were distinctly thicker and longer 

 than those of the fowls dead of fowl cholera. 



Measurements of the bacilli of the blood or spleen 

 tissue, or of cultures in dried and stained cover-glass 

 specimens, showed : — 



