176 



:\riCRO-ORGANIS:\T,S AXD DISEASE [chap. 



present. Dr. Dupre ^ has shown tliat the presence or 

 disappearance of o.xygen (air) dissolved in water is a precise 

 gauge, in the first case of the absence, in the second of the 

 growth, of microphytes. 



In many species one or both ends of the rods, or the free 

 end of the rods forming the terminals in a chain, are swollen 

 and thick, spherical, pear-shaped, or club-shaped (Fig. 50) ; 



Fic. 51. — Film Specimen of Ti'dercle-Bacilm from a Gl^'cerine-Agar 



ClLTL'RE S0:\IE WEEKS OLD ; SHOWING BRANCHED JMyCELI A L-LIKE FILA- 

 MENTS WITH Club-shaped Sproutings. 



occasionally there are some elements, in the middle of a 

 shorter or longer chain, swollen, spherical, or oval. Such 

 forms are considered as involution forms, but I have good 

 grounds for doubting this, and the reasons will be stated 

 later on in connection with the evolution of bacteria. When 

 in a chain of rods, i e. in a thread, the individual rods 

 ^ Report of the Medical Officer of the Local Government Board, 18S4. 



