220 BULLETIN OF THE 
have studied and the youngest larva he figures. They differ from the stages 
which he figures in the presence of the tentacle which always characterizes the 
taster. A failure to raise one of these tasters separated from the colony into a 
new colony, it might be said, does not prove that under other conditions better 
results may have been reached. As a question of opinion, it is regarded as 
highly doubtful that the colony of Nanomia reproduces by budding, and that 
the new colony is ever formed from a taster. Nanomia, however, as shown by 
Agassiz, has an egg development, and passes directly from a planula-like young 
into stages similar to the youngest which he figures. It is therefore thought 
that the embryo, without exception, is derived from an egg. The segmenta- 
tion of the egg was observed, and, as nothing has ever been published on the 
egg of Nanomia, a few stages in the segmentation are here represented. 
The egg of Nanomia, like that of Agalma and other genera, is transparent, 
colorless, almost invisible in the water. The interior is penetrated by and 
almost wholly made up of a spongy mass of protoplasm, forming a network 
filling the contents of the egg. A thin covering of protoplasm surrounds the 
ege. Metschnikoff * describes in the egg of Epibulia a similar network, and 
the author ¢ has devoted some space to a consideration of the same in Agalma. 
The first change (Plate II. Figs. 1, 2) in the external contour of the Nano- 
mia egg is the formation of a primary cleavage-furrow. This furrow was formed 
by the bending in of the outer wall of the egg at one pole. This infolding of 
the primary furrow leads to well-marked folds on the outer wall of the egg, 
which recall the phenomenon of “ Faltenkranz” in some other animals, In 
about an hour’s time after the first appearance of the infolding to form the 
primary furrow, a 2-celled cleavage stage was formed, and the first cleavage 
plane (1 cl) is well developed. About another hour elapses before the sec- 
ond cleavage plane is formed and a well marked 4-cell stage (Figs. 4, 5) is 
developed. 
In his paper on the development of Agalma the author points out the pecu- 
liar warping of the first cleavage plane by the formation of the second. It 
was there shown, that by the growth of the second cleavage furrow at right 
angles to the first, it was brought about that the plane of the first cleavage 
was broken near the equator of the egg. In the same way and by an analogous 
process in the development of the Nanomia egg the second cleavage plane is 
so formed that the continuity of the first plane is likewise broken. Figure 4 of 
Plate IT. illustrates this broken condition of the plane in Nanomia. Whether 
this modification is of any morphological importance, or has any influence in 
subsequent development of the cells, cannot be at present determined. The 
8-cell stage is produced by the formation of two new furrows (Fig. 6) bending 
in on one side of those cells already formed in a way analogous to that already 
described in Agalma. 
* Studien iiber die Entwickelung der Medusen und Siphonophoren. Zeit. f. 
Wiss. Zool., Bd. XXIV. 
+ On the Development of Agalma, Bull. Mus. Comp. Zoél., Vol. XI. No. 11. 
