8 E. V. COWDRY 



larly so on account of Motta-Coco and Lombardo's statement 

 that the granulazioni fucsmofiU occur withm the nuclei. Never- 

 theless, the bodies which they find in the cytoplasm may be 

 mitochondria; those described by Levi certainly are. 



It may well be asked why the observations dealing with mito- 

 chondria in nerve cells are so scattered and so few? The reasons 

 are technical, psychological and theoretical. 



The fixatives in general use for the study of the nervous sys- 

 tem exercise a destructive action on mitochondria. Mitochon- 

 dria are completely dissolved, for instance, by the acetic acid 

 in Carnoy's 6:3:1 fluid. It is on account of this property that 

 the acetic acid in the mitochondrial fixatives devised by Benda, 

 Meves, Bensley and others is reduced to a maximum of a few 

 drops only. Fomialin generally destroys them unless its action 

 is modified by the addition of some other ingredient. Regaud 

 combines potassium bichromate with it for this purpose. Alcohol 

 and corrosive sublimate are also bad fixatives for mitochondria. 

 And conversely the chemicals best adapted for the preservation 

 of mitochondria, like osmic acid and potassium bichromate, are 

 but little used in neurological technique because of their poor 

 penetration. The concentration of attention upon the nucleus 

 and nuclear changes made this condition of affairs worse because 

 the very chemicals which destroy mitochondria give the clearest 

 nuclear detail. 



The observations which first laid the basis for our present 

 conception of the significance of mitochondria were those of 

 Benda ('99) on sex cells. The unfortunate lack of correlation 

 between neurologists and psychiatrists, on the one hand, and 

 general cytologists, on the other, has resulted in the former 

 ignoring the significance of these observations of Benda, followed 

 as they were by the important work of Meves, Duesberg and 

 others, for more than a decade. The position assumed by hema- 

 tologists is quite analogous, because we are only now, largely 

 through the efforts of cytologists, beginning to hear som.ething 

 of mitochondria in blood cells. 



Meves ('08, p. 845) advanced a theory which has exercised a 

 dominating influence upon the trend of mitochondrial investi- 



