A COMPARISON OF MITOCHONDRIA IN PLANT AND ANIMAL CELLS

Abstract

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 experimental 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 Algæ, 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 individual 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 composition is much the same in both plants and animals, but here our knowledge is for the most part supposition and inference, since direct chemical analyses are obviously out of the question. Their composition, as indicated by solubility with respect to acetic acid, heat and other agents, is certainly subject to similar variations in both. Their physiology is obscure; but their wide occurrence in all protoplasm and their general similarity in all places must mean something. It may mean that, in addition to certain specific functions like the production of chlorophyll, they all have a common duty or pant to play in some fundamental vital manifestation like protoplasmic respiration.