516 ARTHUR WILLIAM MEYER 



are occasionally eight to fifteen centimeters long in adult animals, 

 such an origin would seem possible only on the supposition that 

 considerable growth or elongation takes place in the vessels 

 or filaments. Nevertheless, since the latter were observed in 

 various stages of transformation such an origin becomes a highly 

 probable one. This supposition was fully confirmed by a case 

 in which one of the omphalomesenteric vessels was found attached 

 to the apex of the bladder between the extremities of the hypo- 

 gastric arteries in a cat about one year old. The end attached to 

 the bladder had undergone fibrous transformation but the proxi- 

 mal portion still contained a remnant of the original lumen and 



Fig. 25 Obliterated omi^haloniesenteric vessel from a kitten 18 to 26 days 

 old. No remnant of the original hunen is visible and the whole structure is com- 

 posed entirelj' of a vascular connective tissue. X275. 



communicated with the superior mesenteric vein near the central 

 end of the latter. In a second case, that of a cat one and a 

 half to two years old a long, fine vessel containing blood through- 

 out its entire extent was found with similar attachments. This 

 vessel which ran among the coils of intestine likewise joined the 

 superior mesenteric vein near its central end. It was quite uni- 

 form in diameter, about three-fourths of a millimeter thick, 

 and took its origin in three fine veins on the sides and ventral 

 surface of the apex of the bladder. Just cranial to the latter 

 this surviving omphalomesenteric vein which had secured a 

 secondary attachment was attached to the abdominal wall by 

 an isolated fold of peritoneum 2.5 cm. wide and 2 cm. long al- 

 though it was wholly free throughout the rest of its course. After 



