The Development, &c., of Diatomacee. By Dr. G. C. Wallich. 71 
jected to pressure, but’ invariably at the suture, or at the extremi- 
ties where the foramina already described exist’ ” (p. 308). 
As thus described, but reckoning from within outwards, this so- 
called “ simple cell” consists:—1, of the cell-contents or general 
mass of endochrome; 2, of the superficial layer of that mass con- 
solidated into “a sort of primordial utricle” ; and 3, of the “ proper 
cellulose wall interpenetrated and consolidated by silex.” Whilst we 
are called upon to believe that, in order to admit of an indispen- 
sable interaction between the cell-contents and the medium in 
which the organism lives, there actually do exist apertures in stated 
parts of the discoid and elongated genera, but that these are, after 
all, “not absolute perforations in the siliceous envelope, but merely 
points at which the siliceous impregnation is wanting.” 
It is not so stated by the author of the above description, but I 
presume it is left to be inferred, that the absolutely indispensable 
relation between the interior and the exterior of this “simple celi” 
is maintained through the imperforate cellulose membrane at the 
minute points where the siliceous material is absent, by osmotic or 
dialytic action. 
Such a combination of structure, mysterious as it certainly 
appears, is no doubt conceivable. But I confess that to my mind 
it seems so pregnant with incongruity and so incompatible with the 
simplicity of Nature’s ordinary methods of going about her work, as 
to force on me the conviction that it is in the highest degree impro- 
bable. At all events, I venture to say that, by pining our faith to 
such a doctrine, we incur the grave risk of sacrificing fact at the 
altar of mere hypothesis. Nay, even assuming, for the sake of 
argument, the necessity of the case, as here stated, to be met in the 
manner suggested ; in other words, assuming that the maintenance 
of the life of the organism may be thus provided for, it neither does, 
nor can it by any means within our experience, account for all the 
extra-frustular phenomena presented to us in these humble organ- 
isms. It does not, and, what is more, it cannot, account for the 
movements of the diatom, or the secretion of the gelatinous and, in 
some instances, highly elastic membrane-like investments which in 
some are patent enough to our vision, and in others we are per- 
fectly warranted in believing to be present, though as yet we have 
failed to render them visible. And, to say the very least of it, it is 
in no small degree perplexing to have to accept as truths the exist- 
ence of “apertures” that are the moment afterwards said to be no 
apertures, but only the exposed points of an imperforate cell-wall! 
But inasmuch as the day has long since gone by for ignoring 
the logic of cause and effect, I may be allowed to point with a 
sense of triumph to the closely analogous case, very recently pub- 
lished in the ‘ Proceedings of the Royal Microscopical Society, 
namely, that in which the long suspected but never before seen 
