184 ARCHER, ON ASTERIDIA. 
Now, although in the second instance (the first here men- 
tioned) in which I had found these curious-looking spinous 
or stellate bodies I was unable to trace them back to a 
Penium, their identity in appearance in every way, and the 
fact of their having been found distributed in pairs (as if 
left behind by the dissolved or decayed outer membrane of 
a Penium) seems most strongly to indicate that both were 
one and the same thing, and, in fact, that in both instances 
these spinous bodies owed their origin to Penium digitus. 
These bodies are, in fact, the ‘‘ Asteridia”’ of the Penium, 
to adopt Shadbolt’s and Thwaites’ term as applied to the 
still enigmatical stellate or spinous bodies occurring within 
the cells of other Conjugate, and, like such similar bodies, 
these, too, must be regarded, I apprehend, as parasitic 
growths. These are, indeed, altogether unlike the smooth 
rounded or irregularly shaped, opaque, brownish, spore-like 
bodies often seen in various species of Desmidiz, whose nature 
continues equally problematical. The latter, indeed, may 
be possibly refated to Chytridium (Al. Br.) or to Pythium 
(Pringsh.). 
In the same gathering I presently noticed likewise a num- 
ber of slightly smaller green and smooth cells, in some of 
which a directly transverse well-marked light line could be 
seen, indicating a commencing self-division. A few such 
bodies were seen loosely invested by a colourless coat, which 
coat was externally covered by slender spines; these loose 
external coats stood off somewhat from the inner spherical, 
smoothly bounded bodies ; the latter afterwards made an exit 
by a large rent in the spinous outer coat. 
Now, Pringsheim records a similar condition in certain 
“ Asteridia ” in a Spirogyra,* and I have myself seen the 
same slipping out by a rent in the spinous outer coat of the 
Asteridia in a Mesocarpus, and the commencing self-division. 
Therefore, be the true nature of the so-called Asteridia (Shad- 
bold, Thwaites) what it may, there can be little doubt but that 
the bodies I describe belonging to Peniwm digitus are of one 
and the same nature. 
Thwaites + and Pringsheimt seem to hold that these 
bodies are not at all formed at the expense of the contents of 
the cell of the Confervoid in which they occur, and yet they 
both seem to regard them as of truly parasitic nature. If the 
former view be correct, they could not be parasites in the 
* «Zur Kritik und Geschichte der Untersuchungen tiber das Algen- 
Geschlecht,’ p. 46. 
+ ‘Annals of Natural History,’ vol. xvii, p. 262. 
t Loc. cit., p. 47. 
