Fritsch, Observations on the young, plants of Stigeoclonium Kütz. 381 
Berth., evidently also recognised the connection between the purely 
epiphytic type and the forms, which now and then may live endo- 
phytically. 
Klebs (96, p. 399, foot-note) has also advocated the inclusion 
of the genus Endoclonium in Stigeoclonium. Im his opinion the 
Endoclonium polymorphum of Frank (83, p. 365—374) is only a 
Stigeoclonium, which Frank brings into connection with a proto- 
coccoid form !} without sufficient proof. 
The epiphytie species, which I discussed in the third part of 
this paper, was never observed to live endophytically. On the other 
hand I have observed a certain Alga, living within the membrane 
of Cladophora and which seems possibly to be connected with the 
‚Sf. nanum from the pond. It occurred in the same water side bv 
side with this latter species. 
Some of the filaments of the C’/adophora, referred to, presented 
a very remarkable appearance, evident already under a low power 
of the microscope. The original contents of the COladophora-cells 
were entirely hidden — often on all sides of the filament — by a 
compact, parenchymatous stratum, composed of large cells of rounded- 
polygonal shape (Pl. XII, fie. 35). In most cases these cells mereiy 
formed a single layer, but at some poimts twö or three layers 
occurred one above the other; the extreme was reached. when the 
cells were aggregated into a compact mass, which bulged out from 
the Cladophora-filament to such an extent, as to exceed the diameter 
of the latter. The cells of the Alga apparently adhered very close- 
ly to the Cladophora, for pressure on the cover-glass, as well as 
protracted teasing, never resulted in the loosening of any portion of 
the parenchymatous stratum. 
In many cases it was quite evident, that the cells, forming this 
stratum, were actually situated within the walls of the cells of 
the Cladophora (cp. Tab. XII, figs. 33, 34), — between the cuticle 
and the inner layers of the membrane. Probabiy the cuticle is burst 
off later on (cp. Huber 92®, p. 323, foot-note), and the cells of 
the endophyte then appear to be epiphytic: in many cases at all 
events there was no membrane, distinguishable outside them. 
In the early stages, — in which distinet, branched filaments 
eould be made out?), — the chlorophyll formed a thin parietal layer 
in these cells; the central portion of the cell remained almost colour- 
less, except for a few connecting strands of chlorophyll- containing 
protoplasm. Later on, however, the chloroplast forms an irregular, 
eontracted mass in each cell, oceupying a central or lateral position 
(Tab. XII, fig. 36); it also takes on a darker, brownish-green tint. 
To this is due the curious appearance of the Cladophora in some 
places; under a lower power of the microscope its filaments are seen 
to be dotted all over with brown masses, which, when examined 
1) In the original description of Endoclonium by Szymanski the endo- 
and epiphytic portions are not described as nearly so distinetas inFrank’s 
species. 
2) These filaments later on give rise to the parenchymatous siratum in 
just the same way as the parenchymatous base is formed in the epiphytic 
species (e. g. St. farctum, see part III), — that is by continuous branching 
and ultimate coalescence of the branches. 
