1912.] The Life-history of Cladothrix dichotoma (Cohn). 345 



y Grande Eossi(l) describe as Cladothrix in vulnerabilis an organism with a 

 branched mycelium and "aerial 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), 

 Naunyrn (16), Tchierchke (19), and Fliigge (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 Biisgen (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 Biisgen 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 

 Piadais (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 Cladothricaceae. This exception is Sphwrotilus natans; the 

 inclusion of this organism and Cladothrix dichotoma into a single group 

 (called Sphserotilus) by Migula(lo) 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 neighbour- 

 hood 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 neighbour- 

 ing cemetery that is situated on a slight eminence. This accounts for the 

 comparatively high amount of organic matter in solution in this water. 



Analysis of the Water. — This showed that in all respects the water was of 

 the same character as a very dilute sewage. In addition, it contained a small 

 amount of ferrous salt in solution, and of course a large amount of the insoluble 

 red ferric hydroxide which imparts the characteristic colour to streams of a 

 ferruginous nature. 



G-eneral Characteristics of Cladothrix dichotoma. — The organism consists 



