30 THE GROUSE DISEASE chap. 



that in one case they produce offsprings with flagella 

 and in the other without. I have not examined them 

 with regard to demonstrating the presence or absence 

 of flagella, and therefore cannot say positively that it 

 is not so, but it seems to me more probable that 

 the loss of motility is due to some chemical poison 

 produced by the bacteria. In the fresh blood of 

 grouse (dead in the late summer and autumn) the 

 bacteria are always present, as I shall point out 

 below, and motile forms, though not very abundant, 

 can nevertheless be easily detected. So also in the 

 fresh blood of animals and birds infected by inocula- 

 tion with the cultures of the microbe (mice, guinea- 

 pigs, yellow-ammers, and buntings), motile forms can 

 be found. In the grouse and in the sub-cultures from 

 the grouse the oval forms abound. Some are so 

 short that they appear like cocci ; but it must be 

 added that, though at first sight many appear like 

 spherical cocci, on more careful focussing with high 

 powers it can be shown that in reality most of 

 them are oval, but appear spherical when viewed 

 foreshortened or in optical transverse section. In 

 sections through the liver or lung of the grouse 

 dead of the disease, or of other animals infected 

 with the cultures, the blood capillaries, as men- 

 tioned above, are found plugged with the microbes. 

 Now it is precisely in such masses that the individuals, 



