Smith on Asteridia. 
tion, to a single cell, which subsequently, by the ordinary 
method of self-division, becomes elongated into a filament 
('Histoire des Conferves d'Eau douce,' Geneva, 1803, p. 66, 
et seq., PI. IV. 5, V. 3, VI. 4). I have been able, by personal, 
observation, fully to confirm the observations of M. Vaucher in 
reference to one species of the Conjugates (' Ann. Nat. History,' 
2d S., vol. viii., p. 480), and have no hesitation in accepting the 
facts as of general import in reference to the entire family. I 
have alluded to the circumstance, not only as having a direct 
bearing upon the subject of this paper, but also that I may 
explain my reason for not employing the term " Sporangium " 
in reference to the bodies in question, it being evident that 
this designation is not applicable to a body which is in itself 
a single germ. 
With regard to the stellate bodies to which your attention 
is now more particularly requested, their true character being 
for the present doubtful, it will be better to employ a desig- 
nation which does not involve any reference to their nature, and 
has regard merely to their form, I shall therefore speak of 
them as Asteridia, their general appearance being that of 
circular, star-like bodies. 
The presence of asteridia is by no means confined to the 
family of the Conjugato!. I have frequently noticed them in 
the DesmidiecE, and occasionally in the Diatomacece, though in 
these tribes the presence of spinous processes is by no means 
a constant character. I have always found (and Mr. Shad- 
bolt's experience seems to be confirmatory, /. c, p. 166) that, 
if present in a gMhering when first made, the numbers of 
asteridia rapidly increased when the Algce were retained in 
vessels for future examination, and as more or less of change 
and decay almost invariably attends the attempt to preserve such 
organisms in a limited space, and removed from their natural 
habitats, I have hitherto regarded the presence of asteridia as 
indicative of disease, as being, in fact, a parasitic, perhaps a 
fungoid growth, consequent upon the degeneration of the cell- 
contents. 
I am not prepared to put forward this as the true character 
of asteridia, but I am prepared to dispute a view of their 
nature which confounds them with the reproductive germs, 
and shall proceed briefly to state the reasons why such a 
character and function are altogether inadmissible. 
It is well known that conjugation in the AlgcB implies the 
union of the entire contents of two cells, which contents inter- 
mix and become condensed into the reproductive spore, and 
that this union is effected by the amalgamation of the contents 
of two contiguous cells in the same filament, or by the same 
