1876.) A Remarkable Life History and its Meaning. 649 
detached from the tube and escape into the water as a chain, 
the animals of which are now able to provide for themselves and 
| ew very rapidly. Meanwhile another set is developed upon 
the tube of the solitary form, to be cast off in turn, so that the 
(Fie. 48.) 
(Fie. 49.) 
tunic of nurse ; c, wall of 
1,blood-channel of nurse ; 
tozoa ; 
(Fie. 55.) 
wall of breathing chamber of 
‘ood yolk; 9, germ yolk; 10, 
i (Fie. 54.) 
“8. 51-55. Successive stages of segmentation: c, 
Orifice Cavity of same; 1, blood channel; 4, yolk ; 8, ose 
~ © of blood sac; 11, invagination orifice; Å, breathing cavity of nurse. 
