350 
ARTHUR DENDY. 
(b) The Embryos. 
As already stated, the embryos are all in pretty much the 
same stage of development, although varying in diameter from 
about 3 mm. to nearly 5 mm. The immense size of these 
embryos as compared with those of other Sponges has already 
been noticed by Mr. Carter 1 (7), but he says scarcely a word 
about their structure. 
While out dredging with Mr. Wilson I picked a number of 
these embryos out of the living Sponge with forceps, and tried 
the effect of at once placing in fresh sea-water, but I could 
detect no signs of motion of any kind. 
All the embryos were solid, with the exception of one or 
two of the smaller ones. These when examined in spirit 
appeared to be hollow, but they were damaged, and I believe 
the hollow character was a post-mortem condition 2 due to the 
escape or shrivelling up of the very delicate gelatinous, or 
probably in the youngest stages more or less liquid, tissue 
from the interior. I shall therefore not consider them apart 
from the remainder. 
When the surface of the embryo is examined with a pocket 
lens it exhibits a minutely punctate appearance, due to the 
presence of an immense number of shallow pits, somewhat 
polygonal in outline, and separated from each other by low 
ridges (fig. 18). Sections show that each one of these pits is 
the imprint of one of the large epithelial cells of the embryo 
capsule. The pittings were present, in parts at any rate, on 
the smallest embryo examined, but they were not nearly so 
well marked as on the older embryos. All my further observa- 
tions were conducted by means of sections. 
The embryo consists of an outer layer of rather large, closely 
packed cells enclosing a mass of clear, transparent, jelly-like 
substance, in which immense numbers of amoeboid wandering 
1 Mr. Carter says : “ The largest embryo I have seen in the marine Sponges 
is that of Stelospongus flabelliformis, Cart., .... where it is spherical 
and one sixth of an inch in diameter.” 
3 Cf. Quasillina. 
