310 THE AMERICAN NATURALIST. [Vor. XXXVI. 
the long axis of the stock. In a graduated series proceeding 
from the left side of the cluster of youngest buds are more 
advanced buds, the largest approaching the mature condition 
(Fig. 9, 6—2°). At an early stage the anal cirri attain a nota- 
ble length and become articulated. 
As shown in a frontal section (Fig. 9) Dauh the pro- 
liferating region, the buds sprout from a mass of undifferen- 
tiated tissue traversed by muscle fibers which are continuous 
- 
9$ 92,9 * 
ayers ® s s 

Fic. E Fides section of a portion of "m same bud as shown in Fig. ro. z., nerve to 
cb.); vd 7., Optic nerve; 7., na, eure rod Uh and pigment (7.) ; v7., “‘ vit- 
reous i tir " insepiddl of the clear peri. The nerve to the brain breaks up into 
numerous Shere, which are distributed to the a ura Q)cell. x 153. 
with the longitudinal muscle bands of the buds (Fig. 9 A, /.m.). 
This mass is mesoderm, covered by ectoderm in the form of 
epidermis. Both ectoderm and mesoderm of the buds are con- 
wea tinuous with the same germ 
à layers of the proliferating 
...vt. region. Whether the prolifer- 
ating mass comprises one or 
more than one somite cannot 
be positively stated from the 
sections at hand, which are 
ies ee zuo defective at this point. 
an invagination of the epidermis (&A). Letter- — Ata very early stage the meso- 
ing as in figure; Z,lens. x 267 i ‘ 
derm undergoes segmentation, 
and the reproductive cells are discernible (Figs. 9, 9 B, 0’). 
No buds provided with special natatory setze (Pubertdtsbor- 
sten) such as usually occur in the stolons of syllids and in 
the sexual buds of Sy//is ramosa! were observed. 

1 M'Intosh. Challenger Reports, vol. xii, p. 201, Pl. XXXIV A, Fig. 9. 
