1 78 Oscar Riddle 



original^ stained fat goes, we believe from our experience, the stain 

 will go also; the tell-tale color of the Sudan betraying at once both 

 the presence and the source of the fatty materials in transforma- 

 tion. We are thus enabled to study such aspects of fat metabo- 

 lism as involve transfer, and re-deposition of fat, etc., which have 

 been open to almost no other means of attack. Indeed, few organic 

 constituents of the body other than the fats, are open to such 

 methods of study even now. The sum of our present information 

 shows quite clearly that the Sudan holds to the constituent fattv 

 acids even when the integrity of the fat molecule is lost; this, dur- 

 ing its transfer within the body fluids, through practically all of 

 the membranes of the body, and during re-synthesis, in whatever 

 part of the body this may occur. In all these states and relations 

 the pigment maintains the union; apparently only during the oxi- 

 dation and final destruction of the fat is the alliance broken. How 

 far the oxidation must proceed before the disunion occurs, the 

 writer is unable to say. 



The facts already brought forward concerning the behavior of 

 Sudan in several aspects of fat metabolism furnish some solid 

 ground upon which to base a discussion of the transmission and 

 "inheritance" phenomena involved in the passage of Sudan into 

 the egg and the embryo. We can get a clear vision of this field of 

 fact if vve now focus on two points: What are the processes con- 

 cerned in the en trance of the dye into the egg, and in its re-distribu- 

 tion in the newly arising cells of the embryo? How do these pro- 

 cesses compare and contrast with processes known to be involved 

 in inheritance and developmental phenomena? The answer to 

 these questions should bring into relief a safe estimate of the sig- 

 nificance of the transmission phenomena in question. 



The facts absolutely support the view that the passage of the 

 stain through the follicular membrane, which has here been shown, 

 is in no way unlike its passage through the intestinal epithelium 

 or any other membrane. The Sudan, playing here an entirely 

 passive role, is taken mechanically to whatever point the fat goes 

 and remains with the fatty acids wherever they again become 

 anchored through resynthesis into fat. The processes involved 



" This holds true apparently when the fat is lightly stained. Statements made elsewhere furnish 

 the necessary qualifications, and the evidence. 



