112 



BACTERIA. 



peristaltic action of the muscles of the intestine. It thus 

 passes into the body cavity or into other tissues, Avhere it 

 is immediately attacked by the white blood corpuscles, or 

 by the connective tissue corpuscles ; or it may first become 

 developed into the rod-shaped vegetative form. When it 

 has once commenced to divide it is no longer attacked by the 

 above cells (which Metschnikoff speaks of as the phagocytes) of 

 the insect. If the Daphnia is in moderately good health the 



. **# *% 



Photomicrograph of Rosahefe. x 1000. Rose-coloured yeast (?) No spores 

 have been found, and Hansen does not classify it with the yeasts. 



monospora is gradually overcome, but if the insect is feeble, 

 or if the monospora is ingested in very large quantities, it 

 multiplies so rapidly that the animal may eventually succumb 

 to its attacks. This form is specially interesting from the 

 fact that it afforded some of the strongest proofs of Metschni- 

 koff 's phagocyte theory that he was able to obtain. 



We have already seen that the yeast-cell is usually 

 observed in a fermenting liquid as a rounded or ovoid body, 



