The Development, &c., of Diatomacex. By Dr. G.C. Wallich. 79 
Nearly twenty years have since passed, and yet, strange to 
say, these words might with almost an equal amount of truth be 
now re-echoed. If this fact is to be regarded as a source of regret 
in one sense, it becomes, at all events, a source of congratulation 
in another, since it enables me to dive at once into any new matter 
that I may have to communicate on the subject. 
Unless a number of significant facts, which have come under 
my notice in various parts of the globe, and have one and all 
seemed to point to the same conclusion, have been wrongly inter- 
preted, an extraordinary misapprehension has, from the very outset, 
attached to the conception of what the so-called “ Sporangial Frus- 
tule” of the Diatomacez really is; and to this misapprehension 
may, in all probability, be ascribed the failure on the part of 
observers to detect the sequence of results which they looked for as 
the natural outcome of a preconceived, but (as I with all submission 
conceive it to be) a faulty theory. 
If my idea is correct, the sporangial frustule, instead of being, 
as heretofore assumed, the primary or parent frustule of a new 
and vigorous generation, constitutes, in reality, the expiring phase 
in the life-cycle of a generation that is passing away. In 
short, it is nothing more or less than the homologue of the 
“Sporangium,” that is to say, the Sporangial cet of the Des- 
midiacez, which contains and, for a time, shelters- the germs 
of the coming generation ; but is itself doomed, on the liberation of 
its living contents, to death and immediate decay. So that here, as 
in almost every other point, the close resemblance in organization, 
and in the methods by which the Nutrition, Multiplication, and the 
Reproduction of these two families of Protophytes are carried on, 
seems at every step to be more and more firmly established. And I 
need hardly point out that the term “sporangial frustule ” becomes 
in this case only the more appropriate, since we must regard the 
monster frustules, with all their palpable eccentricities of shape and 
marking, not as the parent frustules of a new generation multiply- 
ing directly by division from it, but as an intermediate frustular 
condition, produced, of course, from the fusion of the cell-contents 
of a varying number of normal frustules (as described by writers) 
and, as before stated, constituting the homologue of the sporangial 
cell of the Desmidiacexw. (See back, para. top p. 63.) 
My limits will not admit of my now furnishing a detailed 
description of the facts on which this conclusion is based. Suffice 
it to say that the facts are numerous, and as conclusive as any facts 
ean be which it is practically impossible for us to trace out from 
first to last, as we can in the case of the Monads and Infusoria. 
In these the entire reproductive processes are sometimes begun and 
completed in as many hours as they oceupy days in the Diatomaceex. 
Mr. Smith, in ‘ The Synopsis,’ speaks of twenty-four hours asa likely 
