236 
F. E. Frit sell. 
landicum), the base is relatively insignificant, whilst the upright 
portion attains to considerable development; in others ( e.g ., M. 
farctum, Berthold 1 * ) the base (Fig. 1, b ) is predominant and of con¬ 
siderable extent, whilst the upright system is reduced to short 
filaments and hairs, the filaments being but little branched. The 
writer has recently described a Myxonema prostratum? in which the 
creeping base (Fig. 1, e) is of still greater extent (covering several 
square millimetres of the substratum) ; large areas of this base are 
without any upright system whatsoever (apart from very scanty 
hairs), but at remote intervals there arise tufts of 3-5-celled 
branchlets. 
From the available evidence it seems that one and the same 
species of Myxonema may exhibit a very varied relative develop¬ 
ment of base and upright system under different circumstances, 
i.e., a species may be prevalently upright or prevalently prostrate, 
according to the conditions of the habitat. An investigation of the 
methods of germination of the zoospores in this genus has shown 
that whereas some first form a creeping base, from which the 
upright threads subsequently grow out, others only form upright 
threads, either lacking the base altogether, or only producing it at 
a later stage, 3 phenomena which again illustrate the varying 
importance or the two parts of the thallus in this genus. 
Before proceeding, it will be well to refer to one feature of the 
Chaetophorales, to which undue value might be attributed, viz., the 
production of hairs. These are, undoubtedly, a marked charac¬ 
teristic of the group, although completely lacking in some forms, 
and of very varying development in many. The tendency towards 
differentiation of the ends of the branches as hairs may be regarded 
as one indication of morphological elaboration. We can, however, 
also look upon it as an expression of the tendency towards reduc¬ 
tion of the upright system, of which the hairs become the sole 
representatives in the almost completely prostrate forms to be 
dealt with in the following. It is questionable whether the peculiar 
sheathed hairs, characteristic of such forms as Coleochcete and 
Chcetosphceridmm , are to be considered as belonging to the same 
morphological category as the simple hairs of other Chaetophorales. 
It is not out of the question that the different types of hairs may 
1 Nov. Act. K. Leop.-Carol. Ak. d. Naturf., XL., No. 5, 1878, pp. 201, 202. 
3 F. E. Fritsch, in Annals of the S. Afr. Museum, IX., 1917, 
3 cf. Berthold, loc. cit., also Fritsch, in Beih. Bot. Centralbl., XIII., 1903, 
p. 372, etc. 
