THE GENERAL FUNCTIONAL SIGNIFICANCE OF 

 MITOCHONDRIA! 



E. V. COWDRY 



From the Anatomical Laboratory, Johns Hopkins University 



Years ago Schultze defined protoplasm as being a glass-like, 

 semifluid material in which granules are embedded. Only 

 now are we beginning to see more clearly, for investigators have 

 succeeded, in the last few years, in separating from this baffling 

 heterogeneous complex a class of granulations which are more 

 or less distinct chemically, morphologically and physiologically 

 and which occur in almost all protoplasm. These granules 

 are usually called 'mitochondria.' They are not a recent dis- 

 covery for both Flemming and Altmann observed and described 

 them, but recent studies have enabled us to define them more 

 accurately and have in consequence forced us to revise our 

 views of cell structure. 



MORPHOLOGY AND NOMENCLATURE 



Mitochondria vary in form from granules (0.2/^-2^) to rods 

 and filaments, which may be straight, curved or even forked. 

 Sometimes they are ring-shaped, pear-shaped and possess bleb- 

 like swellings. Networks rarely occur. That mitochondria 

 collectively undergo changes in form was early recognized through 

 the study of successive stages of histogenesis, particularly of 

 spermatogenesis. But it remained for the Lewises ('15, p. 

 352) to actually follow the form changes of individual mito- 

 chondria by the observation of living cells in tissue cultures, 

 to see filamentous mitochondria changing to granular ones, etc. 



The Lewises also observed that the mitochondria moved 

 freely, and quite rapidly, from place to place in the cytoplasm. 



' Aided by the Carnegie Institution. 



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