Report on the Bacteriology of Water. 2H1 



filament, I am strongly inclined to refer the breakage in the above 

 cases to mechanical causes, e.gr., the resistance offered by the gelatine. 

 Indeed, I have watched a long filament in broth, thus abutting on 

 another, and seen it curve until bent into more than half a circle 

 (evidently owing to intercalary growth between the two relatively 

 fixed ends) and then suddenly snap at one of the septa, and the two 

 freed ends dart past each other owing to the elasticity of the filament 

 which had given way. At the same time, there is a period when the 

 (much older) filaments are peculiarly apt to break up into shorter 

 segments, preliminary to spore formation, and this must be due to 

 other causes than mere fracture due to mechanical pressures or 

 tensions, indeed, even in the above cases I do not suppose that the 

 mechanical strains do more than determine the sudden rapture at a 

 septum already prepared to give way, but which probably would 

 not yet have done so had the filament been able to continue its onward 

 growth in a more or less straight line. 



Formation of Tresses. 



I have already described one mode of formation of the strands or 

 tresses composed of numerous filaments lying parallel to one another, 

 by means of the sliding growth of the two pieces of a ruptured 

 filament one over the other. 



Perhaps an even more common process is the modification of this 

 figured in fig. 14 a to i, a series followed under the microscope 

 (E occ. 4) on a broth culture at 17'5 to 19'5 C. The culture was the 

 same as that from which figs. 9 and 13 were obtained, and, in fact 

 just as fig. 13 represents particulars of the growth of one of the 

 filaments developed from the spore of fig. 9 (and traced in that figure 

 for the first thirteen hours of germination) followed from the twenty- 

 fourth to the twenty-sixth hour from germination, so this fig. 14 takes 

 up the further history of the same filament from twenty minutes 

 later through another four hours; for the left-hand filament in fig. 

 14 a is the upper end of the filament e, fig. 13. 



We left this at 12.10 P.M., having traced its growth and nuta- 

 tions during the preceding two hours. At 12.30 the distal end of 

 another filament, segmented off lower down, was seen to be curving 

 over towards the one referred to, and half-an-hour later (fig. 14 6) 

 the tips of both were in contact and growing up alongside one another. 

 I was strongly inclined to suspect the existence of a slight attraction 

 between them from the relatively strong curvatures towards each 

 other which they exhibited previous to contact, but could not be sure, 

 and thought possibly tho phenomenon was of the nature of a merely 

 physical action. During the next hour (fig. 14 c, d, e) a longer and 

 longer stretch of the growing, curved, right-hand filament laid itself 



YOL. LVII1. X 



