16 GENERAL MORPHOLOGY AND BIOLOGY. 



septa which demarcate the individuals of a filament. There is 

 further often a definite membrane or sheath common to all the 

 elements in a filament. Not only, however, is there this close 

 organic relationship between the elements of the higher bacteria, 

 but there is also interdependence of function ; for example, one 

 end of a filament is frequently concerned merely in attaching the 

 organism to some other object. The greatest advance, however, 

 consists in the setting apart among most of the higher bacteria 

 of the free terminations of the filaments for the production of 

 new individuals, as has been described (p. 5). There are vari- 

 ous classes under which the species of the higher bacteria are 

 grouped ; but our knowledge of them is still somewhat limited, 

 as many of the members have not yet been artificially cultivated. 

 The beggiatoa group consists of free-swimming forms, motile by 

 undulating contractions of their protoplasm. For the demon- 

 stration of the rod-like elements of the filaments special staining 

 is necessary. The filaments have no special sheath, and the 

 protoplasm contains sulphur granules. The method of repro- 

 duction is doubtful. The thiothrix group resembles the last in 

 structure, and the protoplasm also contains sulphur granules ; 

 but the filaments are attached at one end, and at the other form 

 gonidia. The leptothrix group resembles closely the thiothrix 

 group, but the protoplasm does not contain sulphur granules. 

 In the cladothrix group there is the appearance of branching, 

 which, however, is of a false kind. What happens is that a 

 terminal cell divides, and on dividing again, it pushes the prod- 

 uct of its first division to one side. There are thus two termi- 

 nal cells lying side by side, and as each goes on dividing, the 

 appearance of branching is given. Here, again, there is goni- 

 dium formation ; and while the parent organism is in some of 

 its elements motile, the gonidia move by means of flagella. The 

 highest development is in the streptothrix group, 1 to which be- 

 longs the streptothrix actinomyces, or the actinomyces bovis, 

 an important pathogenic agent. Here the organism consists of 

 a felted mass of non-septate filaments, in which true dichotomous 

 branching occurs. Under certain circumstances threads grow 

 out and produce chains of coccus-like bodies from which new 



1 Lachner-Sandoval has pointed out the impropriety of the employment of the 

 term "streptothrix," and instead, clearly justifies the use of the term "actinomyces " 

 for all members of this group. 



