207 







B 



Fig. loo 

 Self-determination of degenerative development in the chick mesonephros. 



A, After 5 days as a chorio-allantoic graft, the mesonephros-rudiment shows 

 marked progressive differentiation. The figure is of a grafted short section of the 

 trunk; similar differentiation is obtained with isolated mesonephros -rudiments. 



B, After 7 or more days, the graft shows regression. All secreting tubules have 

 disappeared. The malpighian capsules persist, as in normal development. (From 

 Dstnchakofi, Zeitschr.f. Anat. u. Entwgesch. LXXiv, 1924.) 



