84 THE MITOCHONDRIAL CONSTITUENTS OF PROTOPLASM. . 



the nerve-cell, the distribution of the mitochondria is unaltered by centrifuging 

 (KeyO- There is no reason to believe that the mitochondria themselves are 

 different. At any rate, where the method is applicable ({. e., in egg-cells) the 

 mitochondria are heavier than protoplasm, in which respect they conform to what 

 we know of phosphatids and differ sharply from oils and neutral fats, which rise to 

 the surface and float instead of being thrown down. 



(6) Mitochondria act as solutes for various substances. They are often 

 pigmented and assume the most brilliant hues. Prenant (Asvandourova, 1913, 

 p. 293) has actually styled them " chromochondria " on this account. This solu- 

 tion of other materials in mitochondria is particularly frequent in plant cells. It 

 may or it may not be significant from the point of view of their constitution. 



(7) There seems to be a certain correspondence between variations in the 

 histological picture of mitochondria and the variations in the phospholipin content 

 of the same organ on chemical analysis. Thus Mayer, Rathery, and Schaeffer 

 (1914, p. 612) have been able to alter the mitochondria experimentally in liver- 

 cells. In stages with more mitochondrial substance, chemical analysis showed an 

 increase in phosphorized lipoid; in stages with less, a diminution. Faure-Fremiet 

 (19126, p. 347) has extracted from the ovaries and testes of Ascaris a phosphatid 

 with properties identical with those of mitochondria in the cells of these organs. 



(8) Russo (1912, p. 215) has apparently been able to increase the number of 

 mitochondria in the oocytes of the fowl by the injection of lecithin. R. Van 

 der Stricht (1911, p. 435) found that there are two different kinds of eggs in the 

 cat, one containing much vitellus and the other containing only a small amount; 

 and, further, that, following intraperitoneal injections of lecithin, the relative num- 

 ber of female offspring increased noticeably. In the normal condition 62 per cent 

 are males, while after treating in this way only 23 per cent are males. That is to 

 say, the administration of lecithin increases the amount of deutoplasm in the eggs, 

 increases the number of eggs with much deutoplasm as contrasted with those with 

 small amount, and in this way increases the percentage of females in the offspring. 

 While this is of great interest in the determination of sex, and will be discussed 

 in that connection, it is also of importance as an indication of a possible relation- 

 ship between the amount of mitochondria and the phosphatid lecithin. The re- 

 searches carried on about the same time by Whitman, and subsequently by Riddle, 

 in the determination of sex in pigeons, are in complete accord with these observa- 

 tions of R. Van der Stricht. Riddle (1916, p. 389), in summarizing the results 

 of a long series of studies, points out that, in the first place, the eggs of late summer 

 and autumn produce mostly females and that their yolks are larger than those of 

 the spring, which give rise chiefly to males; and secondly, that old, "overworked" 

 females tend to produce female offspring earlier and earlier in the season, and that 

 this, also, is correlated with larger egg-yolks. His chemical analyses showed that 

 the storage metabohsm is higher and the water-content lower in these female- 

 producing eggs than in those which give rise to males. The general conclusion, 

 of course, is that sex is conditioned by variations in rate of metabohsm, which is 



'Personal communication. 



