245 
I here is no connection between the cushion-shape of some polyps and their possible 
fertility, as is supposed by some authors ; I saw polyps with a very large but entirely empty 
gastral cavity, without a trace of ova or testes. 
In view of the lack of ontogenetic data I examined every polyp closely for eventual 
states of development of eggs or larvae, but I nowhere found a trace of them. 
Growth of the colony. Besides the apical growth of the colony and the interpolypar 
growth I find in Eucirripathes contorta a forming of young polyps on the peristome of an 
adult polyp. Here the mouth originates before the tentacles; one of the young polyps lacks 
every tentacle, but has an actinopharynx with a complete set of mesenteries except the sixth 
pair. Only one of the young polyps has sagittal tentacles. The free borders of the actino- 
pharynges of the young polyps are connected with that of the adult polyp. These young 
polyps have already well developed ovaria. — Probably the same mode of growth explains the 
existence of small tentacles on the oral cone, as is described by me on p. 130. — Apparently 
this peristomal growth is rather rare. 
As to the development of the polyps in the normal manner, I found in one case that 
the lateral tentacles also appear rather late, in any case after the sagittal tentacles and after 
the appearance of oral cone and mouth. — The secondary mesenteries were absent, so that 
they are formed later than the other three pairs, which were already present. 
Parasites. With several species I find symbiotic Algae (diameter 7 — 10 p) in the ento¬ 
derm of the tentacles, the actinopharynx, the bodywall, etc., even of the mesenteries. The 
ectoderm of tentacles, oral cone and bodywall contains smaller ones (diameter 3 p). In one 
species they are colourless, with a diameter of 5 — 7 p. — Several species contain a unicellular 
parasite in the ectoderm (as with Eucirr. contorta ), or in the entoderm of the tentacles with 
some species. One species has much larger unicellular organisms, free in its gastral cavity. In 
one case a Plathelminth was observed in the gastral cavity. 
Dimensions of the layers. Usually the tentacles have the thickest layers, and here 
the ectoderm is the best developed of the three. The mesogloea usually diminishes in thick¬ 
ness from the tentacle-base towards the top, where the mesogloea is sometimes all but absent. 
The layers of the oral cone are of the same thickness as in the tentacles or only a little less. 
The other part of the bodywall usually is much thinner, sometimes to a high degree, i. e. 
Eucirr. translucens where the tentacular layers are resp. 105 p, 140 p and 150 p, against 
40 p, 14 p and 18 p in the bodywall. — The mesogloea may attain an enormous thickness 
in the entire polyp, as is demonstrated by Eucirr. anguina , but especially by Stichop. gracilis 
and Eucirr. translucens. 
The actinopharyngeal ectoderm usually is thick (of the same order as the tentacles) 
while the mesogloea is very thin and the entoderm is like that of the bodywall. Sometimes 
the mesogloea is exceptionally thick ( Stichop. semiglabrd). — The mesenteries usually have a 
very thin mesogloea, and an entoderm like the bodywall. 
The ova are from 65 to 400 p, so rather large; the testes-follicles are about 100 p 
in diameter. 
The axis-wall is much thinner than the radius of the lumen ; it should be kept in view 
