60 
the whole becomes invested, at this stage, with a delicate transparent 
polypary. The column continues to grow longer, and now presents 
at intervals a shallow constriction. The coenosarc which fills its 
axis is at first a simple tube with its endoderm and ectoderm ; but it 
soon becomes resolved into the distinct tubules which characterise 
the coenosarc in the stem of the adult.* The currents in these 
tubules are very evident, but are quite independent of one another— 
sometimes they may be all seen running down, sometimes running 
up ; some down in one or two tubes, up in the others ; sometimes the 
current will be very active in some, and at rest in the others. 
From the basal disc small tubular filaments are prolonged to 
constitute the commencement of the matted root-like base of the 
mature colony. 
From the parts of the stem where the constrictions show them- 
selves, short, thick processes are shot out alternately at each side, 
so that the stem now presents a slightly zigzag form. From the 
upper side of each process a pair of the peculiar little cup-like organs, 
characteristic of the adult zoophyte, are produced, and on its ex- 
tremity the first joint of the polypiferous ramulus makes its appear- 
ance. This joint is soon followed by another, and the ramulus 
gradually elongates itself by the necessary multiplication of joints. 
We have now a condition of the zoophyte very remarkable from the 
fact of its polypiferous ramuli presenting a strictly alternate arrange- 
ment, no tendency to the verticellate disposition of these ramuli in 
the adult being yet apparent. 
Beyond this point I have not been yet able to follow the develop- 
ment of the young Antennularia. 
* In the main stem of the adult, the disposition of the coenosarc is very 
peculiar. Instead of forming a single tube, it consists of numerous separate 
tubules, each with its ectoderm and endoderm. The tubules lie close upon the 
polypary, and leave an unoccupied space in the axis of the stem. They are 
connected to one another by an extension of the ectoderm, which thus forms a 
continuous lining of the polypary. In some parts the tubules of the coenosarc 
run straight and parallel to the axis of the stem, in others, they are more or 
less curved, and frequently connected by transverse but irregular branches, so 
as to present a reticulated arrangement. The motion of the contents of the 
tubules can be distinctly witnessed in them. This complex structure of the 
coenosarc disappears in the ramuli, the separate tubules here giving place to 
the ordinary simple tube. 
