42 FRANK R. LILLIE. 



Fig. 4 is a view of the embryo in the amnion, drawn from the 

 under side of the blastoderm. The vitelline blood vessels are 

 attached to the center of the defective hind-end, the jentire trunk 

 back of these vessels being absent. The amnion is well dis- 

 tended ; its line of attachment is indicated by the dotted line. 

 Just behind this line of attachment is seen a little tag, the hind- 

 end of the intestine. No trace of the hind-limbs is visible ex- 

 ternally. 



This embryo was cut into sagittal sections. In these there is 

 no trace of the hind limbs, and no evidence that the posterior 

 myotomes or sclerotomes are modified towards the formation of 

 limbs. The embryo is not quite so far advanced in development 



FIG. 4. Defective embryo (experiment 93) in the amnion; part of the folded 

 under surface of the blastoderm is shown. A, amnion ; /, ectopic intestine ; V, 

 vitelline arteries and veins. 



as that of experiment 125, but it is certainly old enough to show 

 the rudiments of the hind limbs or any part of them, were there 

 any tendency towards their formation. 



Study of the sections shows that there are only five pairs of 

 post-brachial ganglia and nerves (Fig. 5), the fifth on both sides 



