188 PROCEEDINGS OF SOCIETIES. 
the different forms of Diatomacere (for instance), are to one 
another. 
Again, as regards the so-called conjugation, how is it that, “ the 
animals being the same,” not only does Difflugia unite with 
Difflugia, and Arcella with Arcella, and Euglypha with Euglypha, 
but these seemingly only specifically with each other? It is true 
that Dr. Wallich alludes to an instance of this phenomenon taking 
place between Difflugia and another smaller one regarded as a 
distinct species. Now, in this present gathering, besides the very 
many instances of forms alike in size as well as outer characters 
conjugating with each other, several examples presented them- 
selves quite like that so well figured by Wallich (* Ann. Nat. 
Hist.,’ 3 ser., vol. xiu, pl. xvi, fig. 39); and it would seemingly 
never otherwise suggest itself than to look upon the smaller 
individual as simply but a smaller and younger individual of one 
and the same species. It has been said, indeed, that this process 
iS not a conjugation or union in any sense of the word at all, but 
merely a budding-off—that is, that a portion of the original 
animal becomes simply extended through the frontal aperture, then 
clothing itself with a test, and afterwards separating from the first, 
as a distinct individual. But how is it that no intermediate stages 
present themselves? All the specimens in contact are of full size and 
figure in ninety-nine cases of a hundred, and never an unclothed 
or partially clothed one seems to be found united with a fully 
clothed one. It might, perhaps, be @ priori thought that so lowly 
organized a creature could have no power of electing amongst its 
neighbours only another individual of its own species with which 
to unite. That such an idea would be too hasty, indeed, is seen 
when we find them able to a great extent to select the materials 
of their habitations. But when about to conjugate we cannot 
deny to them that they may be impelled by some kind of inherent 
attraction, species for species, when we see vegetables—Meso- 
carpee, Zygnemer, and Desmidiex, finding out and conjugating 
with those only of their own identical species, admitting the pro- 
cesses in each to be analogous.—In one instance two of the 
Arcelle, upon being separated, seemed to have extended between 
them what appeared to be a tubular plicated membrane, proceed- 
ing from the mouth of each test. The great opacity of the tests 
prevents an insight being gained into the internal conditions. 
On the whole, therefore, while Mr. Archer would deprecate 
being supposed as dogmatically setting up his own views against 
those of a Wallich ora Carpenter, yet he thought he might venture 
so far as to say that their arguments, as regards the fresh-water 
Rhizopods only, had not yet convinced him of the total want of 
stability in these forms, and he thought that the considerations he 
here ventured to bring forward could not be regarded as devoid of 
significance or importance. 
Mr. Yeates showed Smith and Beck’s new illumination for 
opaque objects, in which the object-glass is made its own illumi- 
