FUNCTIONAL SIGNIFICANCE — MITOCHONDRIA 425 



Yet no one would invite us to give up the word 'cell' and to sub- 

 stitute a new and more appropriate term in its place. 



Mitochondria may be provisionally defined as substances 

 which occur in the form of granules, rods and filaments in almost 

 all li\dng cells, which react positively to janus green and which, 

 by their solubilities and staining reactions resemble phospholipins 

 and, to a lesser extent, albumins. 



RELATION OF MITOCHONDRIA TO OTHER CYTOPLASMIC 

 CONSTITUENTS 



It must again be emphasized that mitochondria are by no 

 means a recent discovery. Altmann and Flemming undoubtedly 

 observed and described them, but jVltmann grouped other struc- 

 tures, like secretion granulations, under the same heading of 

 'bioblasts' just as Flemming did with his 'fila.' The interstitial 

 granules of Koelliker and the plasmosomes of Arnold as well 

 as the cytomicrosomes of Heidenhain are also in part mitochon- 

 dria. ^ What is new about mitochondria is that they are with- 

 out doubt a more concrete class of cell granulations than any 

 of the above mentioned. Investigators were not slow to ap- 

 preciate the value of the work of the older authors, in fact the 

 confusion which is so woefully apparent, at the present time, 

 in our ideas of the relation between mitochondria and other 

 formed bodies is due to the fact that they went altogether too 

 far in identifying mitochondria with previously described cyto- 

 plasmic constituents to which they are in no way related. This 

 tendency to carry things to an extreme, to overstep the mark 

 completely, is manifested in the study of mitochondria over 

 and over again. 



A case in point is that of the chromidial substance. (Jold- 

 schmidt ('09, p. 107) and his pupils have persistently asserted 

 that mitochondria belong to the category of the chromidial 



' One must be on the lookout for descriptions of mitochondria under the fol- 

 lowing headings also: chondriosparen and chondriorhabden (Benda), ncuro- 

 somes (Held) karyochondria (Wildman), fuchsinophilc granules, plasmafaden 

 (Retzius), plastidulen (Maggi), perineme and pericaryonime (Renaut), sub- 

 stantia granulo-fihuucntosa, etc. 



