450 SPONGES. 
their nutriment is elaborated in no appropriated digestive 
sac, and, like cryptogamous vegetables or algæ, they usually 
ramify and grow in forms determined by local circum- 
stances, and if they present some peculiarities in the mode 
of the imbibition of their food, and in their secretions, yet 
even in these they evince a nearer affinity to plants than to 
any animal whatever.” This argument is certainly very 
favorable to their classification with plants, but there are 
other arguments by zoólogists equally clever in favor of 
their classification with animals. Linnzus seems to have 
changed his opinion several times respecting them. In the 
commencement of his great work he considered them as 
plants, or at all events as very doubtful animals; but in à 
later edition of his "Systema Nature,” he seems to have 
admitted them along with the zoóphytes in the animal king- 
dom. In the opinion of Pallas, deBlainville, and others, 
they are intermediate organized bodies, without any deter- 
minate form, and with little susceptibility of feeling, but 
presenting an absorbent surface, and nourished pretty nearly 
like vegetables by the surrounding medium.* 
ponges consist of a Satie, or skeleton, coated with 
gelatinous matter, and forming a non-irritable mass, which 
is connected internally with canals of various sizes. The 
ova are very numerous, and present in appearance the form 
of irregular shaped granules derived from the gelatinous 
matter, which grow into ciliated germs and falling at matu- 
rity into the small canals, are then expelled by the orifices. 
. When alive the body is covered by a gelatinous film, which, 
being provided with cilia causes a current of water to pass 
in at the smaller pores and out at the larger apertures, the 
Te probably assimilating the nutritive particles whic 
ter into the water. Papers have been written from time 
to time endeavoring to prove that the pores palpitate, but 
. this has been eed denied, and perhaps the cause of their 
2 ocu M 
P — 3 


: ithe songes ae, by the most advanced zodlogists, considered to be undoubtedly — 
animals; all all botanist: — Editors. 




