Fig. 1. Total preparaticn of very young bud, shov;ing evagi- 

 nation of ectodern and partition of stolon. B. 4. 



Fig. 2. Slightly older bud, seen from right side. 3. 4. 



Fig. 3. Still older bud, seen from right side, and shov/ing 

 anterior elongation and constriction of the stolon- 

 ic connection. B. 4. 



Fig. 4. Bud, seen from right side, at a stage when devel- 

 opment of peribranchial cavity, pericardium and di- 

 gestive tract is well advanced. B. 4. 



Fig. 5. Bud, considerably older than last, shov/ing exten- 

 sions of peribranchial cavity, formation of gill- 

 slits, and further development of digestive tract. 

 B. 4. 



Fig. 5. Transverse section of stolen, showing double-v-'alled 

 partition. F. 2. 



Fig. 7. Transverse section of stolon at point v:here a bud 

 is beginning to form. The ectoderm on one side 

 is thickened, and the double-walled partition is 

 much thickened and dilated. F. 2. 



Fig. 8. Transverse section through very young bud and sto- 

 lon, at about the stage of Fig. 1. The' walls of 

 the partition are coming togetner to close off the 

 inner vesicle. "'esodermal cells are found lying 

 against the outer surface of the latter. ?. 2. 



Fig. 9. Transverse section through posterior end of bud at 

 about the stage of Fig. 3, showing thicke^ned v;all 

 of inner vesicle on right side, and beginning of 



