THE MITOCHONDRIAL CONSTITUENTS OF PROTOPLASM. 71 



role, if any, in determining the shape of the initochondria in the Uving organism. 

 The mere presence or absence of high osmotic tensions within the cells makes no 

 difference, because in certain plants pressures as high as 13 atmospheres are 

 developed, yet, as far as our observations go, the mitochondria difTer in nowise 

 from those in plant and animal cells at atmospheric pressure. 



It is quite possible that variations in the acidity or alkalinity of their surround- 

 ings may affect their form. Bearing in mind the fact that the mitochondria are 

 supposed to be a combination of hpoid and albumin, we might conceive of acidity 

 acting upon their protein fraction, causing it to become hygroscopic and to swell. 

 But we must remember that oxidized phospholii)in has a much greater affinity for 

 water than the unoxidized (Mathews, 1915, p. 98). It is possible, then, that with 

 increase in oxidation initochondria will take up water and swell. But acidity 

 inhibits oxidation. It begins to look as if we had two antagonistic influences to 

 deal with. Acidity may cause the protein fraction of the mitochondria, which is 

 the smallest fraction, to take up water; but it will also prevent the oxidation of the 

 phosphohpin and prevent it from taking up water. So that, arguing along these 

 lines, one would expect the bchaA'ior of mitochondria to depend upon the relative 

 proportions of phosphohpin and albumin, or (more properly speaking) of protein, 

 in their composition. But here we meet with the same difficulty as in the case of 

 osmotic pressure. The astonishing neutrality of the organism would prevent this 

 factor, if it is one, from playing any great part. 



We must simply acknowledge our ignorance and hope for the future. It may 

 be said, however, that the shape and size of the cell have no influence upon the 

 shape or size of the contained mitochondria; neither has the water-content or the 

 consistency of the cytoplasm. 



We may conclude by saying that ^■ariations in the shape and size of mito- 

 chondria constitute by far the most delicate criterion of cell injury known to us. 

 Mitochondria react long before the nucleus, and their morphology is the first thing 

 to change, though it is soon followed by alterations in distribution and in amount. 



