392 MARGARET R. LEWIS AND WARREN H. LEWIS 



by an amitotic division of the nucleus without a coincident 

 division of the cytoplasm. 



In regard to the structures of the differentiated cell, such as 

 muscle fibrillae, etc., we have no observations to offer. How- 

 ever, from the behavior of the mitochondria in various shaped 

 cells it is quite evident that any change which affected the 

 morphology of the cell might also change the position of the 

 mitochondria in such a way that they might appear to be con- 

 nected with the formation of the differentiating structure. 



DISCUSSION 



We have made no attempt to formulate a theory from the 

 above observations in regard to the origin or function of the 

 mitochondria. A review of the literature shows that the mito- 

 chondria have been found in ahuost every kind of cell. They 

 are present in the oocyte and spermatocyte (Benda '97, Van 

 der Stricht '00, Meves '11, and others) and are carried over by 

 the spermatozoon into the egg cell in fertilization (Benda '11, 

 Meves '11); they are abundant in cells of the young embryo 

 (Meves '08, Rubaschkin '11); thej^ occur in plant cells as well 

 as in the cells of most animals, including certain of the Protozoa 

 (Lams '09, Duesberg '10, Meves '04, Guilhermond '12). It is 

 claimed that they form certain cytoplasmic structures such as 

 the fibrillae of the connective tissue (Meves '10), the neuro- 

 fibrillae in the growing neuroblast (Hoven '10), the myofibrillae 

 (Duesberg '10, Torraca '14) the fibrillae of the epithelial cell 

 (Herxheimer '89, Korotneff '09, Faure-Fremiet '10, Firket '11); 

 that they play a part in the process of cornification (Firket '11); 

 that they form the secretory granules, directly or indirectly, in 

 the salivary (Regaud and Mawas '09, Bouin '05), gastric 

 (Schultze '11), mammary (Hoven '11) and other glands (Schultze 

 '11). They are described in the rods of the urinary tubule 

 cells (Schultze '11, Regaud '08), in the intestinal cells (Champy 

 '10), in the liver cell (Policard '09). They may form the test 

 of the foraminifera (Faure-Fremiet '13). They are described in 

 connection with the formation of the retina cells (Leboucq '09). 



