CHROMOSOMES AND MITOCHONDRIA 283 



stain seems to be more selective than any other for 

 mitochondria and is of great value for this reason. 



Mitochondria most often appear as spherical 

 or elongated granules about 0.001 mm. diameter. 

 These granules may become arranged in a series, 

 thus forming a chain, and the granules in a chain 

 may fuse into a homogeneous rod. Different forms 

 are present in different kinds of cells or even in the 

 same cell at various stages in its evolution or func- 

 tional activity. Some investigators (Prenant, 1910) 

 maintain that the homogeneous rod is the primitive 

 condition and that the granules are formed by the 

 disintegration of such rods; to others just the 

 reverse seems to be true (Rubaschkin, 1910 ; Dues- 

 berg, 1912). 



The chemical constitution of the mitochondria 

 has been studied by a number of investigators. 

 Regaud (1908) has shown that the mitochondria of 

 the 'seminal epithelium are not histochemically 

 identical. He distinguishes three sorts of granules : 

 (1) those which resist the action of acetic acid and 

 are stainable without being previously immersed in 

 a solution of potassium bichromate, (2) granules 

 which resist acetic acid but require intense chromisa- 

 tion, and (3) granules which do not resist acetic 

 acid and demand chromisation. Faure-Fremiet, 

 Mayer, and Schaffer (1909) have studied the mito- 

 chondria by microchemical and comparative methods 

 and reached the conclusion that they are lecithal- 

 bumins. 



Mitochondria have been noted in all stages of 



