MITOCHONDRIA IN PLANT AND ANIMAL CELLS. 



evolution, their form in Vaucheria (Rudolph, '12, PI. i8,Fig. 9) 

 being equally indistinguishable from that of the oak and of man. 

 This paper shows how much alike they are everywhere. We 

 are tempted to enquire whether the presence of mitochondria in 

 conjunction with a nucleus made evolution possible. This may 

 indeed be true if, as I have already mentioned (p. 223), they are 

 concerned with protoplasmic respiration, which is perhaps the 

 most fundamental of all vital manifestations. Certainly no 

 consideration emphasizes their importance more. 



SUMMARY. 



This comparison of mitochondria in plant and animal cells 

 brings to light a truly remarkable degree of similarity. 



Their reactions to fixatives, stains and supravital dyes are almost 

 identical. Similar fixatives preserve them, modify them and 

 destroy them, in like manner, in both. Even the result of experi- 

 mental errors in the technique is the same. Plant mitochondria 

 react to the janus green test and stain with supravital dyes in 

 substantially the same way as animal mitochondria, though it 

 is certainly more difficult to obtain a good coloration. 



Their distribution is almost universal. They occur in all plants 

 with the exception of certain Algce, Bacteria and Myxomycetes, 

 and no animal has yet been discovered which does not contain 

 them. In addition to this, similar and parallel variations occur 

 in their arrangement in the several tissues and even in the indi- 

 vidual cells of plants and animals. They must, therefore, be 

 regarded as an integral, perhaps essential, constituent of living 

 matter. 



Their morphology is identical in plants and in animals. They 

 assume no forms in the one, which are not present in the other. 

 They undergo similar variations in size and shape in different 

 tissues and in different cells in both. If it were possible to view 

 mitochondria dissociated from their environment, it would be 

 impossible to decide whether they came from plant or animal 

 tissues, provided that they did not contain starch, pigment or 

 some other easily recognizable substance, to serve as a clue. 



We have every reason to suppose that their chemical composi- 

 tion is much the same in both plants and animals, but here our 



