ioo Lectures on Bacteria. [ ix. 



one of the most widely diffused, and most important and varied 

 in its powers of decomposition, the Bacillus of butyric acid, 

 known as B. Amylobacter, van Tieghem, B. butyricus, Clostri- 

 dium butyricum, Prazmowski (22, 47, 48), and by some other 

 names. I think that I ought also to refer Bacillus butylicus of 

 Fitz to this species, though it must be remembered that this 

 species as at present established may perhaps be divided into 

 several on further investigation. 



Bacillus Amylobacter (Fig. 1 3) is nearly i p. in thickness, and 

 vegetates in the form of slender cylindrical rods united at 

 most into short rows, and usually in a state of active movement. 

 It is easy to characterise morphologically, because the sporo- 

 genous cells swell out till each becomes 

 fusiform and then produce inside the part 

 which is most enlarged an elongate ovoid 

 spore with rounded ends and sometimes 

 slightly bent, surrounded with a broad 



^ i 1 I S gelatinous envelope, and much shorter and 



1 m j B usually much narrower than the swollen part 



of the cell in which it is formed. It is also 

 distinguished by the starch-reaction or 

 granulose-reaction described on page 18, 

 which is usually manifested by the cells 

 before the spores are formed, and by its 

 habit, since it does not usually aggregate 

 and form distinct membranes or larger Zoogloeae, and at the 

 period of spore-formation often appears in the form of the motile 

 rods with capitate end, which were likewise noticed on a former 

 occasion (see page 17). Otherwise Bacillus Amylobacter is very 

 morphous; the most different special forms of sporogenous 



Fig. 13. Bacillus Amylobacter. Motile rods, some cylindrical and 

 without spores, some swollen into various special shapes and with spore- 

 formation in the swelling, s mature spore with broad gelatinous envelope 

 and isolated by the deliquescence of their mother-cells. Magn. 600 times, 

 with the exception of s which is more highly magnified. 



