REPORT ON THE GROUSE DISEASE. 335 



state of the liver, which I described in a previous paragraph. As 

 a matter of fact, most of the keepers were firm in the belief that, 

 in all birds dead of the malady this year and in previous years, 

 the liver was found, on opening the animal, in a diseased con- 

 dition. Others who have had experience in these matters, like 

 Mr. Bailey Worthington and others, were of the same opinion. 



The fact that in the two diseased birds which I brought to 

 London, and in which the peritoneum was to all appearances 

 sound, but the liver and kidneys, particularly the former, in a 

 pronounced state of disease, presented an insurmountable diffi- 

 culty, and I may say, in consequence, I altogether abandoned the 

 theory of tapeworm. 



Thus, except having learned from my own observations the 

 nature of the pathology of the diseased birds, I had to confess 

 the status quo ante. 



This being the state of matters, and seeing that the liver is 

 the organ most constantly and distinctly affected, it was necessary 

 to examine this organ microscopically in order to study more 

 carefully the nature of the affection. Two things seemed to 

 me to deserve special attention. In the first place, there can 

 be no doubt that the theory that Grouse disease belongs to the 

 group of infectious or communicable diseases best harmonises 

 with the general pathology above described, and the manner of 

 the spread of the disease, as observed in this epidemic and in 

 former years — viz., that the disease, having made its appeai'ance 

 in a particular localitj^ gradually sweeps, as it were, over the 

 whole of this and the adjoining districts ; further, that the disease, 

 manifesting itself at first in isolated cases, soon becomes epidemic, 

 and then again gradually declines in frequency. 



Secondly, the question of some species of bacteria being the 

 cause of the disease could not be answered in the affirmative. 

 But it was still possible that some other kind of fungus was the 

 cause of the malady, and in this case ought to be discovered in 

 the liver. In connection with this, it is necessarj' to bear in mind 

 that not all communicable diseases are due to bacteria. Amongst 

 these I maj^ mention various forms of Protozoa, Amceha coli and 

 various Psorospermia {Coccidumi oviforme in rabbit's liver) ; then 

 there are various higher Fungi, Favus fungus, Aspergillus Jiavus, 

 fumigatus, and niger ; then several species of Mucorinse, all of 

 which are known to be pathogenic to man and animals ; then 



