Sudan III m Metabolism and Inheritance i8i 



all that lies within a vitelline membrane. Nevertheless the anal- 

 ogy holds: the mass of fat and protein in the egg of the fowl 

 is transmitted from parent to germ. This fat, moreover, neither 

 immediately disappears nor undergoes equal distribution in the 

 embryo, but like the Sudan it persists and becomes specifically 

 localized. 



As an interesting example of such localized persistence the 

 writer cites the toad's egg in which Miss King (08) has pointed 

 out that masses of yolk from the developing egg persist in the new 

 germ cells, and that the yolk masses serve to mark off these 

 germ cells as such. Here occurs a passing over of certain con- 

 stituents from one germ cell to the next generation of germ 

 cells. Of course it cannot be asserted positively in this case that 

 the identical fat molecules of the first egg were contained in 

 those of the succeeding generation. Miss King merely asserts 

 the continuity and persistence of the morphological picture fur- 

 nished by aggregates of such molecules. The transmitted fats 

 however, exhibit one more advanced stage of complexity of be- 

 havior than does Sudan, due to the new combinations they can 

 enter into and the readiness with which their molecules can be 

 both built up and torn down in the organism. 



A second analogy of the transmission and temporary persistence 

 of Sudan we find in the cases of hereditary immunity, observed 

 hitherto chiefly in mammals. In these cases, as is becoming well 

 known, the immunity secured by the foetus through the placenta 

 or germ may be of longer or shorter duration, often covering only 

 a fraction of the span of a single generation. It is from the stand- 

 point of the type of transmission displayed by Sudan that these 

 inherited immunities are to be interpreted. 



Sitowski has given the analogy of the passage of parasites 

 (spirochzetae and other protozoa) from the soma into the repro- 

 ductive cells; the analogy is not complete, as he has pointed out, 

 since in the case of the parasites we deal with living, active forms 

 which seek out the germ cells. Other differences might well be 

 noted. Bacteria also are known to reach germ cells in a similar 

 way. 



Of much more interest and weight is the analogy between the 

 behavior of Sudan and that of the glow substances of the glow- 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY. VOL. 8, NO. 2. 



