THE FOOD OF UKOPODA. 625 



bacillus and the earth bacillus. "Wild yeast-cells were rapidly- 

 devoured, as was also the case with micrococci. There is little 

 doubt but that they eat the gonidia of fungi, because species 

 of Penicillium and Mucor never appeared in boxes con- 

 taining mites in large numbers ; otherwise they were commonly 

 present. 



I employed about ten boxes for cultivating the Uropoda. The 

 mites multiplied freely and appeared very healthy. There was 

 no difficulty in isolating tliem from other species, as the 

 transference from the lily bulbs to potato was a very simple 

 matter. 



The bacteria and other organisms which grew on the potato 

 were sufficient for food, although slimy colonies were not formed 

 if the mites were present in large numbers. 



The plain surface of the potato allowed me to place food in 

 such a way that there was no doubt as to its constitution, and 

 that it was actually consumed by the JJropoda. 



The mites delayed decomposition of the potato, but they were 

 not capable of p'-eventing its final disintegration, because they 

 could not gain access to bacteria which had penetrated deeper 

 than the superficial layers of cells. 



On one occasion I saw many JJropoda engaged in feeding on 

 the dead body of one of their own species. It is possible that 

 they may have been devouring bacteria which were causing its 

 decomposition, 



I am greatly indebted to Mr. A, D. Michael, P.R.M.S., for 

 his assistance. He very kindly named my specimens, which 

 were sent to him from Bermuda where my investigations were 

 conducted. 



