338 Mr. H. J. Carter on the Ultimate 
vent resumes its original dimensions and opens its aperture 
by which two efferent currents are subsequently established, 
for the abnormal one does not close when the normal one be- 
comes opened." 
Dr. Bowerbank also (Brit. Assoc. Advance. Science, Report 
for 1856) notices (“June 10”) the opening of several new 
oscula and the closing of old ones in the piece of Hymeniacidon 
caruncula which he was watching, as if they could be closed 
and extemporized like the holes of the investing sarcodal 
layer when and wherever required. On Pachymatisma John- 
every sponge-body that consists of two persons (7. e. that pos- 
sesses two or more oscula) I denominate a ‘stock’ or *cormus.' ” 
Háckel's theory may suffice for the Calcispongiæ, but I doubt 
if it will apply so generally to the Siliceous Sponges. 
G'enerative Organs. 
What these are in the Corals or Polypes and Tunicata is 
evident. But where are they, and what are they, in the Sponges? 
The seed-like bodies of Spongilla I have long since com- 
pared with the winter-egg of the freshwater Polyzoa (Annals, 
vol. iii. p. 331, May 1859, pl. 8); and the ciliated gem- 
mules appear to me to be only another form of them, while 
all appear to me originally to be but transformations of the 
ampullaceous sac. 
ut what is the ovum and what the spermatozoon of the 
sponge ? 
In November 1854 (Annals, vol. xiv. p. 334) I published - 
(the reader will be tired of my referring to my publications; 
if not, I am) a short account, with illustrations, of certain mo- 
enociliated sponge-cells, which at the time I conjectured to be 
the zoosperms or spermatozoa of the sponge. In 1858 (Annals, 
vol. iii. p. 14, pl. 1, January 1859), on account of the conjec- 
ture, I put this to the test by feeding a suitable piece of Spon- 
qua with indigo, in order that I might see if these monoci- 
iated sponge-cells enclosed any, in which case they might be 
considered not to be spermatozoa, for spermatozoa do not take 
