Group of the “ Physemaria.” 15 
cipated that no one will be more ready than himself to recog- 
nize in it a true though wonderfully simple sponge-type. If, 
on the other hand, he should find it to consist of homogeneous 
sarcode, it is not identical with Prof. Haeckel’s Gastrophy- 
sema, and his first inference, that it must be regarded as a true 
Foraminifer, or, at all events, a Rhizopod, is correct. 
Notwithstanding the remarkable interpretation placed by 
Prof. Haeckel upon the interesting and simple little sponge- 
forms which have received .from him the title of the Physe- 
maria, that authority has undoubtedly greatly advanced our 
knowledge of the Protozoa by his record (so far as structural 
facts only are concerned) and exquisite illustrations of those 
types which have been examined by him. In the faithful 
rendering of the minutest histiological detail his pencil cer- 
tainly has no equal, every stroke speaking to those familiar 
with the object or structure depicted with an amount of elo- 
quence that words would fail to inspire. 
In conclusion, it may bé predicated that, if Prof. Haeckel 
would only recognize in each collar-bearing cell of his exqui- 
site drawings that individuality which it is impossible after a 
long acquaintance to deny them, we should hear no more of 
the “‘Gastrea” theory in association with the sponges. That 
the chief if not the only obstacle to his yielding such recog- 
nition exists through his unacquaintance with these collar- 
bearing cells in their living and active state, forces itself upon 
one’s mind in contemplating all his illustrations of these struc- 
tures that occur both in his magnificent ‘Monograph of the 
Caleareous Sponges’ and the volume containing his descrip- 
tion of the Physemaria. In not a single instance out of these 
is the characteristic “ collar”? portrayed in that symmetrical 
and fully expanded condition which so eminently distinguishes 
it in the living state. Nor on any occasion has Prof. Haeckel 
indicated the presence of the invariably two or more rhythmi- 
cally expanding and contracting vesicles always to be observed 
in the living monads, and which in these types, as among all 
other Protozoa, represent the rudimentary respiratory system. 
His representation of the nucleus of these separate bodies is also 
by no means life-like, but presents all the features of a post 
mortem aspect. A careful investigation of this special struc- 
ture has, in fact, clearly demonstrated that it is by no means 
a constant and essential factor of any Protozoan organism, not 
being, indeed, the equivalent of the nucleus of ordinary tissue 
structure, but merely an accessory to the reproductive act. 
The probability of this element being subservient only to this 
function of reproduction, and of its not being comparable to 
the typical histiological nucleus, has been already suggested 
