22O N. H. COWDRY. 



present the same form and solubilities as true mitochondria in 

 both plant and animal cells. They form granules, rods and 

 filaments which multiply by division. He embedded them in 

 glycerin-gelatin, fixed them and found that they stained in the 

 usual way by the various mitochondrial methods. 



I have myself experimented with lecithin. I made a very 

 fine emulsion, evaporated it to dryness on glass slides and stained 

 with iron hematoxylin. The bodies which I observed resembled 

 mitochondria in some respects but in others differed so very 

 radically from them that I am unable to confirm Lowschin's 

 observations. 



4. The temperature solubility of mitochondria may be also 

 significant because mitochondria, like phosphatids, are thought 

 to have a low dissolving point. Policard ('12, p. 229) observed, 

 in the case of some animal tissues, that the mitochondria are dis- 

 solved when subjected to a temperature of from 48 C. to 50 C. 

 in a moist atmosphere from 10 to 30 minutes, while the other 

 parts of the cells remain practically unaffected; and Koch and 

 Voegtlin ('16, p. 59) remark that phosphatids are notoriously 

 unstable to heat. With the hope that this temperature solu- 

 bility would turn out to be a definite physical test for mito- 

 chondria, I experimented with both the pea and the pancreas, 

 observing the precautions outlined on page 199. I found that 

 in both the pea and the pancreas they dissolve at about the same 

 temperature, that is to say, from 48 to 50 C., when treated for 

 30 minutes. The first change noted is a loss of their filamentous 

 form (see also the Lewises, '15, p. 375); they became granular 

 with indistinct outlines merging into the surrounding cytoplasm 

 and they finally disappeared leaving no trace behind. In the 

 case of the pea, the mitochondrial changes are difficult to make 

 out on account of the production of a confusing coagulation of 

 the ground substance. 



5. The specific gravity of mitochondria is generally greater 

 than that of the protoplasm in which they are embedded (Faure- 

 Fremiet, '13, p. 602). This is determined by the unsatisfactory 

 centrifuge method. When they are thrown down they are said 

 to be of high specific gravity. If the protoplasm is in the physical 

 condition of a gel, rather than a sol, as in the nerve cell, the dis- 



