FUNCTIONAL SIGNIFICANCE — MITOCHONDRIA 435 



on boiling yield gelatin, a protein devoid of tyrosin. One is 

 tempted to enquire by what chemical changes can the mito- 

 chondrial substance, which is supposed to be a phospholipin 

 combined with a small fraction of albumin, form both? There 

 is no evidence that the mitochondria give a positive Adamkiewicz 

 or Millon's reaction. It is, furthermore, difficult to conceive 

 of how pancreatic zymogen, which is presumably the precursor 

 of steapsin, amylopsin and trypsinogen ; mucin, which is a gly- 

 coprotein devoid of iodine; and the colloid of the thyroid, which 

 contains iodine can originate from one and the same substance. 



But the strongest evidence in favor of a change in mitochondria 

 comes from the botanists, because mitochondria can be easily 

 seen unstained in living plant cells and the substances, which 

 are supposed to be formed from them, (xanthophyllous and an- 

 thocyanic pigments, chlorophyll, etc., Guilliermond '13, p. 

 436) are themselves naturally colored. Still it is apparent 

 that the doctrine of an actual chemical transformation of mito- 

 chondria into substances of diverse constitution is weak. 



Regaud ('11, p. 685), perceiving the difficulty, advanced 

 his 'eclectosome' theory^ according to which the mitochondria 

 play the part of plasts, choosing out and picking up materials 

 from the cytoplasm and blood stream, condensing them and 

 converting them, in their substance, into infinitely diverse pro- 

 ducts. Chemical substances are thus supposed to be drawn in 

 from the outside, not to be formed through a transformation 

 of mitochondrial substance. But Regaud goes too far in com- 

 paring the mitochondria to the side chains of Ehrlich, which 

 are even now going out of fashion, and possibly also in endowing 

 them with the ability to choose and select, for it is quite con- 

 ceivable that they may play an entirely passive role in histo- 

 genesis. They may act only as a vehicle or substratum, in 

 which, by virtue of its physical or chemical properties, sub- 

 stances are deposited which are synthesized through the activity 

 of the cell as a whole. 



' This conception is a modification of the famous lipoid membrane theory of 

 Overton, the chief difference being that the lipoid substance is said to be distrib- 

 uted throughout the whole area of the cytoplasm in the form of mitochondria, 

 instead of being confined to a layer on the surface of the cell. 



