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POPULAR SCIENCE REVIEW. 
our shores, and that we had passed direct from the labours of the great 
i gradationalist,’ Baron Cuvier, to those of the German embryologist, such 
as Baer, Beichert, and Bathke. These men did indeed lay a foundation, 
deep and wide, by their incomparable labours, for a true morphological 
knowledge of the Yertebrata. Socrates was accused of corrupting the 
rising youth of Athens by questioning the truth of received axioms, and 
disturbing their unfinished minds with doubts. We may accuse a modem 
and native philosopher, our English Oken, of misleading students — I speak 
feelingly for myself — in the opposite direction, namely, by dispelling whole- 
some doubts by interpreting all the hard sentences of Nature for them, and 
by holding before their charmed vision an Archetypal Idea , instead of 
setting them to work at the various types, with scalpel, and lens, and 
microscope.” 
The new views of Spongilla structure . — Perhaps there is no subject in 
zoology that has been so much explored as that of Spongilla; and even yet, 
notwithstanding the fine papers of Henry Carter, F.B.S., and Dr. 
Bowerbank, F.B.S., and Dr. H. James Clark, there appears work to be done. 
Dr. James Clark has an able paper in Silliman’s 11 American Journal ” for 
December 1871. In this he in great measure confirms Carter’s researches. 
He says that the monad chambers are deep spherical hollows, which form the 
receptacles of the groups of monads. They are mere cavities, and have no 
lining wall. They may be easily recognised, in young specimens, as clear, 
more or less circular, areas scattered in pretty close proximity to each other 
over the u cytoblastemic mass.” Each chamber has a single, small, circular 
aperture which perforates the inner investing membrane, and allows egress 
into the circulatory apartment. The aperture varies in size at times, and may 
even be completely closed. He has never seen it open wider than one-third 
the diameter of the chamber, and very rarely more than one-fifth as wide. 
That it is a true perforation, and not a clear spot, may be demonstrated by 
bringing a chamber into profile, so that its aperture lies on the extreme 
border, and then an actual break in the continuity of the investing mem- 
brane becomes evident. Entering this aperture, we do not meet with any 
obstacle for a little distance around it ; there is a clear open space ; but 
pressing onward beyond that, either to the right or the left or directly 
forward, the cavity appears filled by a collection of vibrating bodies. They 
seem to be arranged radiatingly from and about the centre. Close inspec- 
tion, however, modifies this view, and it turns out that they are based upon 
the periphery of the chamber, and converge towards its centre, where is a 
small unoccupied space. We presently recognise these converging bodies to 
be craspedote, flagellate monads, so closely packed together, side by side, as to 
form a continuous stratum over the whole concave face of the chamber, 
excepting immediately about the aperture. Every feature of the monad is 
strongly marked ; even the cylindrical collar is so heavy and conspicuous 
that its outlines may be seen with as low a power as two hundred diameters. 
Professor Clark has studied these bodies with a |th-inch objective, and 
found it not at all difficult to focus down upon the details of their organi- 
sation without pressing upon or even touching the specimen. 
Does or does not Cliona burrow ? — This question has recently developed 
the opinion of two naturalists : Mr. Ed. Parfit, who asserts that it does, and 
