Chlorochytrium inclusum Kjellm.

1920]	SeteheH-Gurdner: Chlorophyceae	149

on Iridaea from the west coast of Whidbey Island, Washington, shows
small plants (40/1x80/*), broadly pyriform and with thick walls. It
is to be referred provisionally to Chlorochytrium, but does not
agree with Kjellman’s description. No. 514, of Collins, Holden and
SetchelPs Phycotheca Boreali-Americana, shows large, thin walled
cells, depressed vertically and measuring about 160/* by 240/a, seem-
ingly a Chlorochytrium, but not in accord with the descriptions of
either Kjellman or Freeman. The other references given by us, with
the exception of Tilden’s no. 389, which is Freeman’s plant, are to
be rejected. They are found to be based upon plants of the second
type, which is probably Ckytridiaceous, possibly being near to Rhodo-
chytrium. They are probably ? the so-called gland cells mentioned
by Schmitz as occurring in Turnerella Mertensianat (P. and R.)
Schmitz (1896, p. 372) and figured as occurring in Iridaea affinis
P. and R. (Postels and Ruprecht, 1840, pi. 40, f. 93). We have
selected for illustration (pi. 13, f. 1) plants occurring endophytic in
Weeksia Fryeana Setchell collected by Gardner near Sitka, Alaska.
These seem to correspond more nearly than any of our other speci-
mens with the description and figures of Kjellman.

PLATE 13

Chlorochytriwm inclusum, Kjellm.

Fig. 1. A vertical section through the host, showing the penetration of the
endophyte to the medulla. X 250.

nisiER I PLATE 13
UNIV. CALIF. PUBL. BOT. VOL. 8	[ SETCHELL-GAnL'

1. Chlorochytrium inclusum Kjellm. -
Plate 13, fig. 1

Cells in the vegetative condition, spherical or subspherical, entirely
included within the host plant, at the time of the formation of the
zoospores, slightly elongated, depressed conical, ampullaeform, ovoid
or ellipsoid, at length exposed through the penetration of the cortical
layer of the host by the apiculate tip, emitting the zoospores through
an ostiole.

Endophytic in the fronds of various membranaceous algae, e.g.,
Iridaea, Weeksia, Constantines, etc. Probably common along the coast
from Sitka, Alaska, to Puget Sound, Washington.

Kjellman, Alg. Arctic Sea, 1883, p. 320, pi. 31, f. 8-17; Setchell
and Gardner, Alg. N.W. Amer., 1903, p. 206?; Collins, Green Alg.

N. A., 1909, p. 147 (in part) ; Collins, Holden and Setchell, Phyc.
Bor.-Amer. (Exsicc.), no. 514?; Tilden, Amer. Alg. (Exsicc.), no.
389?.

The description, given above, is a fairly literal translation of the
Latin diagnosis of Kjellman, who adds certain details in his remarks.
The original host is Dilsea integra (Kjellm.) Rosenv. (Sarcophyllis
arctica Kjellm.). The cells of the Chlorochytrium are placed, in most

148 University of California Publications in Botany [Vol. 8

cases, near the surface of the host plant but sometimes occur in the
middle layer. In vegetative condition the cells are from 80/x to 100/i
in diameter, the cell wall is thin and of equal thickness throughout,
while the chromatophore is thin and spread over the whole wall.
The wall becomes thicker and apiculate at the outer end as the cell
passes into the reproductive stages, the apiculate wall piercing the
outer cortical tissues of the host. Kjellman states that the contents
divide into a large number of closely packed zoospores which escape
through an opening formed by the dissolution of the wall at the tip
of the cell. These latter statements are evidently inferences because
he distinctly says that he had only dried specimens for examination.

In an authentic specimen of the host plant distributed by Kjell-
man, young cells of the Chlorochytrium were found nearly spherical
in shape, with uniformly thin walls, and with a chromatophore thin
and dotted with numerous large pyrenoids. These cells are about
80/x in diameter.

Upon examining various specimens referred to this species, the
conclusion has been forced upon us that there is some variety of
species and possibly even of genera among the Pacific Coast plants
referred to Chlorochytrium inclusum and it seems practically demon-
strated that no one of those accessible to us is clearly the plant of
Kjellman.

Very little can be accomplished from the study of dried specimens,
but living specimens should be studied to obtain more exact informa-
tion as to structure and development. Our present knowledge, even
of the type, is so slight as to admit of little certainty, and Kjellman’s
statements as to the formation and emission of “zoospores” need to
be carefully verified.

On reexamining the various specimens referred to this species from
our coast, we are able to make only a few general statements.

Freeman (1899, p. 186) describes a plant which he provisionally
refers to Chlorochytrium inclusum, but he found only vegetative
stages. It was endophytic in the blades of Constantinea subulifera
Setchell. In the Algae of Northwestern America (1903, p. 206), we
referred several specimens to the same species. Of these we may dis-
tinguish, at least, two very different kinds of endophytes. The first
kind includes what are probably species of Chlorochytrium, possessing
a single chromatophore with numerous starch centers, while the second
is made up of plants seemingly possessing neither chromatophores nor
chlorophyll and certainly devoid of starch. No. 290, N. L. Gardner,