SrONGOZOA. 
477 
Small cliitinous tube.g, wkicli are external prolongations of a similar invest- 
ment of the whole channel-system, becoming, however, more delicate 
below, and finally passing into a sarcodo-like condition : each of these 
tubes is inhabited by a retractile sac-like body, provided with ectoderm, 
a muscular layer, and entoderm, with thread-cells, and with (1-12 long 
unbranclied tentacles with cilia and tbroad-cclls ; below, they pass succes- 
sively into the common sponge-substance, and generally lie four in each 
channel, each, however, within its own special chitinous tube. In other 
sponges {Reniera?) these polypoids were found in a lower stage of evolution, 
with short or absent tentacles, thread-cells present or wanting, no muscular 
layer, chitinous investment sometimes strongly developed, annular, and pro- 
jecting — in other instances reduced to a delicate, almost sarcode-like mcin- 
brane, or almost totally wanting. The idea of parasitism is, according to the 
author, quite out of the question ; the ^‘polypoids ” he consequently regards 
as the true nutritive zooids of the sponge, and the sponges in which they 
occur in a more rudimentary shape as intermediate forms, leading to the 
great majority of sponges without nutritive zooids of any kind. As regards 
the nutrition of sponges, ho further assorts that he was often capable of 
pressing a thick chymus ” through the mouth ” from the “ stomach ” of 
calcareous and siliceous sponges, and that in most instances he found it to 
contain half-digested remains or the entire sucked bodies of small (but never 
living) Crustacea ; he therefore thinks that sponges partially feed upon 
microscopic Criistacea\ 
Contemporaneously with Hsickel’s discovery of the spermatozoa of Sponges, 
Eimer also discovered true spermatozoids of rather ordinary shape in nu- 
merous sponges (calcareous, siliceous, and gelatinous). These ai*e very abun- 
dant, but have hitherto been overlooked on account of their great delicacy. 
[The author’s obs('rvations are conOrmod by (hiricr, who obsr'vved them iti 
1870: Ann. N. II. (4) vi. pp. 880-810.] As numerous eggs were found i»i the 
same specimens, sponges must be considered hermaphi’odite. In speaking of 
intermediary forms between spermatozoa and ordinary flagellate cells, Eimer 
agrees with Hiickel, who regards the first ns a modified form of the latter ; 
he inclines, however, to the belief that Ilfickel (like Lieberkiihn and Huxley) 
did not observe the fulW developed fecundating elements [?]; but Hackel’s 
assertion, that he observed the act of fecundation, suggests to Eimer tlie 
hypothesis that in some sponges the male element never attains its perfect 
development, but is nevertheless capable of duly performing its functions ! ' 
Observations on the “ zygosis” of the “ Spont/ozoa ” (as Carter proposes to 
term the flagellate or “ monociliated bodies ” investing the interior surface 
of distinct cavities in the sarcodal lining of the areolar cavities), which is 
compared to that of Di^upia, on the development of the young Tethyce 
from the “ovula,” and on that of the spicula are contributed by Carter (4), 
who, in another paper (6), gives the history of w*hat he considers the true 
Sponge-animal ” or “ Spongozoon,” and points out the difference between 
Clark’s views and his own regarding these organic units [which may be 
regarded as definitely settled by Hackel, 
Vhyllosponffiay {Ccrampongia*). Leaf-shaped, thin as paper, 
without larger oscula, with a regular mesh of homogeneous horny fibres of 
equal thickness. Type E. papyracea, Esp., Tranquebar. 
1872. [voL. IX.] 2 I 
