THE BACTERIAL NATURE OF MITOCHOXDRIA 41 



of mitochondria to the cell? Do the mitochondria become 

 a part of the cell cytoplasm, or do they retain their indi- 

 viduahty? The fact that they may be induced to exist 

 independently of the cell would appear to indicate that 

 they do retain their individuahty, but this does not neces- 

 sarily indicate an absolute independence. Again, the 

 observations of Chambers in which he apparently saw 

 mitochondria disappear by mixing with the cytoplasm, 

 has a bearing on the question. It will require special 

 investigations to determine the intunate physical relation- 

 ship of mitochondria to the cytoplasm. The possible 

 reactions of microsymbionts in the cytoplasm of the host 

 cell is discussed in later chapters. 



The evidence for calhng mitochondria bacteria, rests upon 

 the following attributes: Their general behaviour in the 

 cell is sunilar to that of known microorganisms which live 

 symbiotically in the cells of higher organisms; for example, 

 the root-nodule bacteria of legumes. When grown inde- 

 pendently in artificial culture media, they behave in all 

 observed particulars like bacteria. They divide like bac- 

 teria. They are similar to bacteria in structure and shape. 

 They exhibit no cultural characteristics foreign to bacteria. 



