16 HENRIK PRINTZ > | [1920 
io the orientation of the cells to the substratum. The chromatophore 
is a parietal bell, which covers the whole of the inner cell-wall; 
it is without a pyrenoid. 
I have often observed that the contents of the cells by succe- 
«daneous divisions are divided into å great number of daughter cells, 
escaping through åa hole in the mother membrane. Thus, in this 
variety the old membrane does not dissolve into mucilage, which 
seems to be the usual way in this genus according to the information 
on this subject in the literature, for instance by LAGERHEIM, 
Rernscn, and Dr Toni, and empty mother membranes (pl. II, 
fig. 80 and 81) are frequently to be found in preparations of 
this alga. As long as these daughter cells, which must probably be 
designated as aplanospores, are lying within the mother membrane, 
as also at the moment of escaping it, they are entirely smooth. 
Their size is about 2—2,5 u in diameter. The smallest Acanthococcus- 
cells I have been able to recognize by the structure of the membrane, 
measure about 3—4 u in diameter. In so small cells the membrane 
is only very slightly crenulate, however (vide fig. 89. pl. II), and the 
structure can be seen by a very close examination only. Whether the 
small celis on having escaped the mother membrane, are further 
divided and undergo a Palmella-stage, or the like, or whether they 
are real aplanospores directly increasing and growing out into new 
Acanthococcus-cells, I have not had sufficient material to ascertain. 
Personally I am of opinion that the last mentioned thing happens, 
as I have not observed anything that may be explained as divisions 
or Palmella-stages. 
Ås known, the genus Acanthococcus is considered to be a very pro- 
blematic one, and several of the species deseribed as Acanthococcus 
are no doubt only resting cells or phases of development belonging 
to other algae. It is, however, beyond åa doubt that some of them, 
at least, are entirely independent species of algae. If the small cells 
observed by me, escaping the mother membrane, should turn out to 
be real aplanospores, this genus is to be referred to the family of 
Qocystaceae, where its nearest relations must be sought among the 
Chlorella or allied genera. 
This species seems to be å very common aérophilous alga in the 
neighbourhood of Durban. Thus, I have found it in quite a number 
of samples: 37, 99, 105, 109, 122, 134, 138, 171, 237, 252, 272, 279, 
and 313. 
Hormidium flaccidum Braun in RaBENHORST, Algen (1876) no. 
2480. Hormiscia flaccida (Körz.) LaGErRHEr in Flora 1888, no. 4; 
De Ton, Syll. Alg. I, p. 161. [P]. VI, Fig. 233—2431. 
Specimens of this extremely varying and yet by far not eluci- 
dated species or collective species I have found in some samples 
from the environs of Durban (nos. 16, 19, 26, and 238). 
