482 



ARTHUR WILLIAM MEYER 



these have become detached, retracted and degenerated, unless 

 a pennanent instead of a temporary attachment were subse- 

 quently acquired. Moreover, from the findings in these two 

 new-born dogs it seems not at all unlikely that the two pups of 

 the seventh week in whom no remnant of the suspensory liga- 

 ment could be found were also instances in which degeneration 

 and regression of the suspensory ligament had already begun 

 at the time of birth. 



Even in a pup 91 hours old marked changes were plainly evi- 

 dent in the distal portion of the umbilical vein as shown in 



1 



Fig. 1 Degenerating umbilical vein of a lamb 91 hours old. X142. 

 Fig. 2 Plicated caudal border of the suspensory ligament of a rabbit, 

 some portions these folds are fused. X275. 



In 



figure 1. In this case portions of the lumen of the vessel are 

 filled with connective tissue containing some bloodvessels. The 

 degenerating musculature which has undergone embryonic 

 regression has lost its characteristic arrangement and staining 

 qualities and also contains numerous blood vessels but can still 

 be recognized as such. This vessel and these changes will be 

 discussed fully below. 



The degeneration and disappearance of the suspensory liga- 

 ment and the umbilical vein in the cat occur much slower than 

 in the dog and sheep. In the oldest cats examined no remnant 



