THE CAUSE OF GROUSE-DISEASE. 339 



propagation and multiplication within the bodies of these birds 

 of a specific germ. This much Dr. Klein has clearly proved. 

 The chief changes he finds, as Dr. Wilson found, in the lungs, 

 while congestion of the liver is also a conspicuous sign. No 

 germs could be found in the blood of grouse which had died of 

 the disease in June, 1887 (Zool. 1887, p. 334), nor could any 

 microbes be found in the liver, lungs, kidneys, or blood of grouse 

 which had perished in the spring and summer of 1888, 1889, 

 and 1890. But when the same organs (lung and liver) of grouse 

 which have been affected in the spring and early summer are 

 examined, a very definite species* of germ is found, forming, as 

 Dr. Klein tells us, " continuous masses or plugs in some of the 

 capillary (or finest) blood-vessels," while in the blood of the 

 general circulation these germs " cannot be demonstrated." 

 This is nothing unusual in the life-history of germs. There are 

 many germs capable of producing disease which do not thrive or 

 live in the blood itself, but do thrive and multiply in some organ 

 or other, of which liver and lungs are good examples. The 

 bacillus or germ of grouse-disease is of course a microscopic 

 living particle, which in the fresh state is a spherical, or more 

 generally an oval, corpuscle, " occasionally more distinctly rod- 

 shaped or cylindrical with rounded ends." These germs occur 

 singly, or are more commonly double — that is, under the shape 

 and guise of dumb-bells. Most of them seem to possess no 

 movement of their own, though now and then active locomotion 

 is observed, the microbe spinning round or darting through the 

 field of the microscope with an oscillatory movement of its body. 

 In recent cultures of the germ the number of mobile microbes 

 is greater than when the cultivation is of some age, from which 

 fact Dr. Klein draws the conclusion that in the cultures there 

 is produced some chemical substance that inhibits their 

 movements. 



Mice inoculated with the cultivated germ of grouse-disease 

 die in from thirty-six to forty-eight hours. It is incidentally 

 mentioned that the vitality of the germ is great, since cultures 

 made in gelatine and kept for a year and a half proved to be 

 capable of multiplying their kind. This fact has to be kept in 

 mind in view of the explanation of the propagation of grouse- 

 disease from year to year. 



Used to inoculate certain birds, however, the germ of the 



3g3 



