Group of the “ Physemaria.” 3 
I am enabled, through my extended researches into the struc- 
ture and developmental history of the independent collar- 
bearing forms, to follow out the subject to a more decisive issue 
than has yet been attempted. 
Prof. Haeckel, as it is well known, while driven to admit 
the existence in sponge-structures of these collar-bearing cells 
or monads, has altogether refused so far to recognize in each 
such collar-bearing monad a distinct and individual vitality, 
choosing rather to regard the same as the contiguous cellular 
constituents of one out of two multicellular layers or tissues of 
which he considers all sponge-forms are composed. This view 
held by Haeckel would, if correct, approximate the sponges 
more closely to the simplest tissue-forming Coelenterata ; and 
it is exactly such a position for them that he has been endea- 
vouring for some years past to bring into general recognition. 
Taking upon trust, indeed, and dazzled by the garish lustre 
of the learned professor’s brilliant “Gastrea”’ theory, of which 
the “Ceelenteric”” or “ Diploblastic ” interpretation of the 
sponge question must be regarded as the chief corner-stone, 
that recognition has already been very extensively accorded, 
leaving, indeed, as a very slender minority the adherents of the 
Protozoic or Monoblastic interpretation of the organisms in 
dispute. An irreparable gap has further been occasioned here 
through the recent deplorable death, in the midst of his valu- 
able investigations, of Prof. H. James-Clark. The time at 
length, however, seems to have arrived when accumulated 
facts of so substantial a nature can be set in array in proof of 
the thorough agreement of the sponges in every essential 
detail with the representatives of the ordinary Protozoa, that 
the acceptors, upon trust, of the Diploblastic interpretation of 
the question will be well advised to reexamine and work it 
out for their own satisfaction. If upon so doing the results 
realized should accord with and confirm those obtained by the 
writer, the ‘“ Diploblastic ” or ‘ Gastrea”’ theory, so far, at 
least, as the sponges are concerned, will be held henceforth in 
but scant estimation. 
The grounds upon which the above, at first sight somewhat 
presumptuous, anticipation is hazarded, together with the 
bearings upon the question of Prof. Haeckel’s newly created 
group of the Physemaria (embracing,inhis opinion, Mr. Carter’s 
Foraminiferal (?) type Squamulina scopula), may now be 
examined. Before arriving at this more complex aspect of 
the problem, however, it is desirable to devote a brief space to 
an acquaintance with the initial integers of it, viz. the inde- 
pendent collar-bearing flagellate monads in their simplicity, as 
first made known to us by Prof. Clark. On reference to my 
1* 
