The name
Cladothrix dichotoma
was first applied to this organism by Cohn in 1873. In 1875 he also founded the genus
Streptothrix
to include an organism (
S. Foersteri
) which differed from
Cladothrix
mainly in the possession of a mycelial habit. In 1887 the genus
Actinomyces
was also instituted by the same writer, to include the newly discovered
A. bovis
. Whatever may be the value of the distinction made by Cohn between
Streptothrix
and
Actinomyces
, there is no doubt whatever about the clearness of the line of separation which he set up between these genera and
Cladothrix
. Unfortunately, later writers have used the term
Cladothrix
to indicate not only the only organism belonging to the group, but also species belonging to
Streptothrix
. As examples may be mentioned the organism described by Cienkowski (3) in 1877, which he describes as having a branched mycelial habit. The same mistake was made by W inter (21) in 1884. Influenced, doubtless, by these descriptions, Macé (14) in 1884 denied the separate identity of
Streptothrix
and
Cladothrix
. In his work he describes the characteristics of
Streptothrix
, and gives, under this name, precisely those defined by Cohn as belonging to the genus
Streptothrix
. The confusion by this time had become fixed, and we find the same mistake in later writers. Thus Günther and Rullmann (10), in 1896, describe as
Cladothrix odorifera
what is obviously a
Streptothrix
. Again, Acosta and y Grande Rossi (1) describe as
Cladothrix invulnerabilis
an organism with a branched mycelium and “ aërial hyphal threads.” The same indubitable characteristics of
Streptothrix
are to be found in Eppinger’s (5)
Cladothrix asterioides
, and in Hesse’s (2) and Garten’s (9)
Cladothrix liquefaciens
, likewise in the organism described as
Cladothrix
by B. Fischer (7), Kedzior (13), Naunym (16), Tchierchke (19), and Flügge (8). Some investigators had avoided this mistake. The first, since Cohn, was Zopf (22), whose masterly treatise, despite small errors in detail, contains the best morphological account of
Cladothrix dichotoma
which has yet been published. We are also indebted to Büsgen (2) and to Hoeflich (12) for several valuable additions to our knowledge of this organism, and particularly because their observations were taken from pure artificial cultures. To Büsgen belongs the credit of being the first to obtain a pure culture of this species, while the fullness of Hoeflich’s account of growth in artificial media leaves nothing to be desired. On the other hand, the researches of Sauvageau and Radais (18) have put our knowledge of the genus
Streptothrix
on a firm basis. We know now that the two groups are, phylogenetically, very far apart, and that, with one exception,
Cladothrix dichotoma
stands alone in the group Cladothricaceæ. This exception is
Cladothrix natans
; the inclusion of this organism and
Cladothrix dichotoma
into a single group (called Sphærotilus) by Migula (15) is a step the wisdom of which is very questionable.
Distribution
.—
Cladothrix dichotoma
was described by Zopf as the “Wasserpilz par excellence,” on account of its very wide distribution. He referred more particularly to the neighbourhood of Berlin. In the neighbourhood of Glasgow the organism does not thrive particularly well. In waters with a high organic content the predominant place is held by one or more species of the lower bacteria, or one of the higher fungi. In two places only was a predominant growth of
Cladothrix dichotoma
found in waters containing organic matter in solution. From one of these, a ferruginous stream running close to Possil Marsh, near Glasgow, the whole of the present observations were taken. The water which forms this stream is collected from a neighbouring cemetery that is situated on a slight eminence. This accounts for the comparatively high amount of organic matter in solution in this water.
Natural Changes in a Soil of the Mediterranean Climate Under Low Agronomic Inputs
