14 STMBIONTICISM AND THE ORIGIN OF SPECIES 



albumin, being transformed into myofibrils which contain 

 tyrosin. 



The conceptions embodied in Benda's work that mito- 

 chondria enter into histogenetic differentiations, apparently, 

 stimulated a number of investigators to study mitochondria 

 in relation to various histogenetic activities. This point 

 of view was further strengthened by Regaud's ''eclectosome 

 theory," which held that mitochondria behave somewhat 

 hke plasts, choosing and selecting substances from the sur- 

 rounding cytoplasm, and transforming them into diverse 

 products. Meves, in 1910, investigated the origin of con- 

 nective tissue fibrils. He found that mitochondria leave the 

 cell and become filamentous, and he believed that they enter 

 into the formation of the fibrils. Against this conception is, 

 apparently, the work of M. R. Lewis ('17) who studied con- 

 nective tissue fibril formation in tissue cultures. Cowdry 

 criticizes Meves' work from two points of view. He assumes 

 that the chemical composition of the mitochondria of all 

 cells is the same, and that the assumed phospholipin- 

 albumin structure is incompatible with collagen fibril forma- 

 tion. On the further assumption that the mitochondria of 

 all cells are alike and the fact that filamentous or thread-like 

 mitochondria are present in cells which do not contain 

 fibrils, Cowdry holds that the development of filamentous 

 mitochondria in Meves' preparations have no significance. 



Firket ('11) investigated the origin of epidermal fibrils 

 and concluded that they arise from the differentiations of 

 mitochondria. Duesberg later confirmed this work of 

 Firket. Meves, in 1907, investigated the origin of fibrils 

 in nervous tissue. He concluded that the mitochondria 

 of the nerve cells differentiate into the neurofibrils. A 

 number of investigators have also confirmed his work, of 

 whom we might mention Hoven and Arnold. Marcora, 

 Levi, and Gurevitsch, on the other hand, reject the con- 

 ception that neurofibrils are formed from mitochondria. 



