EXPERIMENTAL STUDIES ON MITOCHONDRIA IN 



PLANT CELLS. 



N. H. COWDRY, 



ANATOMICAL LABORATORY OF THE PEKING UNION MEDICAL COLLEGE OF THE 



ROCKEFELLER FOUNDATION. 



INTRODUCTION. 



During the last few years several investigations have been car- 

 ried on with a view to utilizing the mitochondria as cytoplasmic 

 indicators of cell activity. Reasoning on the basis of the funda- 

 mental differences which exist between the mitochondria and 

 the nucleus it has been natural to assume that they may serve as 

 clues to different types of activity. We are accordingly faced 

 with the possibility of studying physiological and pathological 

 processes from an entirely new angle, which may yield valuable 

 and unexpected information. Thus far the results obtained from 

 this new line of work have been contradictory and difficult to ex- 

 plain. On the one hand we have indications that, in certain in- 

 stances, the mitochondria are very labile and respond easily to 

 alterations in cellular activity (Busacca, '15; the Lewises, '15; 

 Homans, '15; Scott, '16; and Goetsch ,'i6) ; and, on the other, 

 equally convincing observations to the effect that, in other cases, 

 they are fixed and permanent cytoplasmic structures which do 

 not evidence distinctive variations even under the influence of 

 fairly advanced pathological conditions (Clark, '14; Strongman, 

 '17; McCann, '18; and Rasmussen, '19, etc.). This condition 

 has filled some investigators with enthusiasm and discouraged 

 others. It should, however, only act as an incentive toward a 

 systematic experimental study of mitochondrial variations. 



Since the substantial similarity of mitochondria in plant and 

 animal cells has already been demonstrated (N. H. Cowdry, '17) 

 we have ample material to choose from. It is possible to apply 

 certain experimental conditions to plants which are not feasible 

 in the case of animals, and vice versa. For the purposes of this 

 paper I have selected the sprouting rootlets of peas because the 



