Mr. H. J. Carter on Spongilla. 4i 



and the focus directed into, it. Thus I imagined it to be a sac 

 with a circular aperture in one part^ and with cilia vibrating in 

 its interior; and so I have given an '^ ideal section" of it*. But 

 my scepticism as to the reality of this apparent aperture con- 

 tinuing, I again grew some Spongilla from the seed-like bodies, 

 in a watch-glass, as before, and having found a very favourable 

 portion for observation, kept it under the microscope while a 

 little indigo was placed in the water, when I noticed that all 

 the particles were taken up by the exterior parts of the " ampul- 

 laceous sacs '* in contact with which they came, through the 

 crevices that exist between them, and none even appeared to go 

 iiito their interior. I therefore inferred that there really was 

 110 aperture in these '^ sacs," and hence that the cilia must be 

 otitside instead of inside them ; and so persuaded am I of this 

 view now, that I would have, in the ideal section of the ampul- 

 laceous sac to which I have referred, the cilia placed outside, 

 the " cortical layer" removed, and the internal lining membrane 

 Attended across the supposed aperture : thus there would remain 

 a! transparent, spherical sac, coated all over by a layer of mono- 

 ciliated and unciliated sponge- cells, except at one part, where 

 the circular transparent area exists ; and hence all analogies at 

 which I have hinted, between this sac and the stomachal cavity 

 of the lowest Polypes, &c., cannot now be permitted, nor the 

 t^rm " ampullaceous sac" retained. For the latter, that of 

 ^^ spherical sac" might now be adopted; but this is an inappro- 

 ^'riate appellation: "sponge-cell" would be better; but then 

 there are at least three kinds of Amoebous cells in Spongilla 

 which might be so termed, viz. the monociliated and unciliated 

 "bells forming the cortical part of the " spherical sac," and the 

 cells of the " investing membrane." Then there is the " seed- 

 'lil'e body," which, again, is an inappropriate term, and the 

 word "gemmule," much worse: "sporangium" would be bet- 

 ter; and the transparent sacs which it contains, with their in- 

 cluded granules (which pass into the monociliated and unciliated 

 cells of each " spherical sac"), would respectively be more intel- 

 ligibly named " spore-cells" and " germs." Yet none of this 

 nomenclature sounds satisfactorily, for the simple reason that 

 Spongilla is as much animal as vegetable, and therefore the 

 nomenclature of neither kingdom suits it, m\^Aun1 .((;!;>,: od't 

 Latterly, since I have directed my attention to the Volvocineaj 

 these seem to me to bear the greatest resemblance to the sphe- 

 rical sacs of Spongilla ; and while we are still unacquainted with 

 the mode of fecundation in this organism, it may not be alto- 

 gether useless to conjecture that the fecundation might be also 

 similar : thus, the spherical sac might become the sporangium, 

 .M ,oU ,({ .ZA ,^. ^j^j^^g^^^,!^ XX. pi. 1. fig. 5, 1857. ■'''^""''' 



