174 BULLETIN OF THE BUREAU OF FISHERIES. 



structed from the study of similar folds. The effort was made to present an accurate picture of the 

 relative amount and distribution of the fat in the cells. The rather regular beaded arrangement of fat is 

 shown in sections of the same fish, fixed in Flemming, in which the fat droplets are stained black in 

 figures 5 and 6. It is also shown in material fixed in corrosive sublimate, where the fat has been dis- 

 solved out, leaving fat vacuoles. The inner ends of the epithelial cells contain only slight quantities 

 of fat. No fat is ever found in the outer borders of the mucous cells. 



The tunica propria is filled with a medium load of fat, the fat being caught in the spaces of the tissue 

 and in the connective tissue cells. This fat is all laid in with the camera lucida. No fat is present in 

 the stratum granulosum, either in the cells or in the supporting coimective tissue. Traces of fat are 

 present in the connective tissue surrounding the blood vessels, and also in the vessel endothelial cells. 

 A few fat droplets are also present in the cells of the muscular coats, especially in the muscularis longi- 

 tudinalis. Magnification, Leitz ocular i, objective 7. 



Fig. 4. — A high magnification of a section through the superficial fold of cylindrical epithelium of 

 the cardiac portion of the stomach showing fat absorption in an early stage of the process. The fat is 

 largely limited to the outer or most superficial zone of the cylindrical cells, but small amounts are present 

 in the basal zone. This salmon had been fed olive oil by the method of rectal injection, the oil passing 

 through the intestine and forward into the stomach. Brookdale young salmon, no. 46. Camera lucida 

 outlines. Magnification, Leitz ocular i, objective 7. 



Fig. 5. — A section of a group of epithelial cells of the pyloric intestine fixed in Flemming's solu- 

 tion to show fat absorption. Young salmon no. 45 from Brookdale, Cal., which had been fed fat artifi- 

 cially. The amount of fat is not so great as present in the section of the caudal length of the intestine 

 shown in figiu-e 4. The same beaded arrangement of fat droplets is shown, but more smaller droplets 

 are present in the ends of the cells — a fact showing either an earlier stage or a slower rate of absorption. 

 Camera lucida drawing. Magnification, Leitz ocular i, objective 7. 



Fig. 6. — Showing fat in the transverse section of a fold of the pyloric coecum of young salmon no. 

 45, the same fish as in figure 2. The salmon was previously fed olive oil by rectal injection and the tissue 

 fixed in Flemming's solution. This section presents a typical picture of fat absorption in the pyloric 

 coeca when the process, is at its height. It is splendidly fixed, sharply stained, and is reproduced under 

 camera lucida with the greatest possible care. Note the fine division of the fat droplets shown in the 

 outer margin of the cylindrical epithelial cells, also the relatively small amount of fat of the zone within 

 the nucleus. The tunica propria contains an excessive quantity of fat, the boundary limit of which 

 is sharply marked by the broad band of the stratum compactum . In this specimen an occasional minute 

 liposome is present in the connective tissue of the stratum granulosum as well as in the muscular coats, 

 a fact that is very seldom shown. Camera lucida outlines. Magnification, Leitz ocular i, objective 7. 



Plate XIV. 



Fig. 7. — Showing fat absorption in the pyloric caecum 18 hours after fat feeding. Young salmon no. 



45. In this specimen fat is crowded in the superficial epithelium, also in the tunica propria. The 

 details of histological structiu'e are largely omitted in order the better to emphasize the great amount of 

 fat present. The droplets in the tunica propria are especially numerous in this particular fish. The 

 stratum compactum forms a sharp outer limit to the fat-bearing zone of the timica propria. Fat-fed 

 yoimg salmon no. 45. Magnification, Leitz ocular 2, objective 3. X4S. 



Fig. 8. — Showing fat absorption in the pyloric coecum 42 hours after fat feeding. Young salmon no. 



46, the same fish from which figure i was taken. The fat is largely removed from the superficial 

 epithelium, except in the tips of the folds, but is supercrowded in the tunica propria. Camera lucida 

 outlines. Magnification, Leitz ocular 2, objective 3. 



Fig. 9. — Showing fat absorption in the pyloric coecum of fat-fed young salmon no. 88, from the 

 McCloud River, Baird, Cal. The structural detail is shown in only one-half the figure. Fat is rather 

 evenly distributed throughout all portions of the cylindrical epithelium and is present in medium 

 amoimt in the tunica propria. There are a few small droplets in the outer muscular coat. Time of 

 absorption, 20 hours. Magnification, Leitz ocular i, objective 4. 



Fig. 10.— Showing fat absorption in the pyloric caecum of ayoung McCloud River salmon no. 91, after 

 70 hours of absorption. This specimen shows the epithelial cells unusually crowded with fat. The fat 

 has not yet reached the tunica propria, although the time for possible absorption is longer than in no. 88 

 of the same experimental series. Camera lucida outlines. Magnification, Leitz ocular 2, objective 4. 



