CHANGES IN FETAL VESSELS OF THE LIVER 515 



even if not necessarily to a contraction of the longitudinal muscu- 

 lature alone as Henneberg concluded. Since the walls of con- 

 tracted vessels as ordinarily seen in histological preparations 

 are sinuous or folded more or less I cannot believe that what 

 was seen in the retracted and contracted umbilical vessels is 

 anything but an exaggeration of the same phenomenon and 

 that both kinds of fibers when present are factors in their pro- 

 duction for the circular fibers are very evidently even if not pri- 

 marily, concerned. Moreover these ridges can be seen in de- 

 generating umbilical vessels which are entirely free in their 

 distal portions and the varying shape and size of these welts 

 makes it impossible to attribute them solely to a varying de- 

 velopment of the longitudinalis. Ridges or Wiilste due to pro- 

 liferation of the intinia were never observed although their 

 occurrence in the ductus arteriosis is not therefore denied. 



A peculiarity often seen in cats two to four months old or 

 older, and more rarely in young dogs, is the presence of one or 

 more extremely fine long peritoneal l)ands about half a milli- 

 meter thick, extending from one portion of the mesentery to 

 another and surrounding a numl^er of coils of the small intestine. 

 Taking their caliber into consideration these bands are unusually 

 strong although fastened only at their ends and are apparently 

 always bloodless. Since it is only occasionally that one end of 

 these filaments is fastened to the peritoneum near the umbilicus 

 it did not seem very probable at first that they were remnants 

 of the omphalomesenteric vessels but since such delicate fila- 

 ments were never observed in very young or old cats such an 

 origin seemed not at all an improbable one. Hence two such 

 strands from a cat ten weeks old, were examined microscopically 

 but neither filament contained anything which could be recog- 

 nized as a remnant of the omphalomesenteric vessels. Both 

 wxre composed of fibrous connective tissue (fig. 25) contain- 

 ing one or two veins and several smaller arteries. By compari- 

 son it will l)e noticed that the structui'c of these cords is very 

 similar to that of the temi)orary roimd ligament of some cats, 

 rabbits and guinea-pigs. Howe\'er. since these fine filaments 



THIC AMBRICAN JOUK.VAI, OI' ANATOMY, VOL. Ifi. XO. I 



