38 



ZOOLOGY 



SECT. 



the tail aborts, and two processes, one postero-dorsal, the other 

 ventral, known respectively as the cadophore (dors, st.) and the 

 ventral stolon (vent, st.), grow out from the body of the larva. On 

 the latter'are formed a number of slight projections or buds. These 

 become^constricted off, and in the form of little groups of cells, 

 each consisting of seven strings of cells with an ectodermal invest- 



FlQ. 746. Doliolum, late stage in the development of the'tailed larva, atr. ap. atrial aperture ; 

 dors. st. cadophore ; end. endostyle ; ht. heart ; ne. gn. nerve-ganglion ; noto. notochord ; 

 or. ap. oral aperture ; vent. st. ventral stolon. (After Uljanin.) 



ment, creep over the surface of .the parent (Fig. 747, e, and Fig. 

 748) till they reach the cadophore, to which they attach themselves 

 after multiplying by division. The cadophore soon becomes 

 elongated, and the bud-like bodies attached to it develop into zooids. 

 As the long chain of zooids thus established is further developed, 



dors.st 



atr. 0.71 



vent si 



FIQ. 747. Doliolum, lateral view of asexual stage, showing the early development of the buds. 

 atr. ap. atrial aperture ; dors. st. cadophore ; e. embryos passing over the surface from the 

 ventral stolon to the cadophore ; ht. heart ; ne. gn. nerve-ganglion ; or. ap. oral aperture ; 

 vent. st. ventral stolon. (After Uljanin.) 



the parent Doliolum (Fig. 747) loses its branchiae, its endostyle, 

 and its alimentary canal ; at the same time the muscle-bands 

 increase in thickness and the nervous system attains a higher 

 development, until the whole parent comes to play a part like 

 that of the nectocalyx of a Siphonophore (Vol. I., p. 161), its 



