Report on the Bacteriology oj Water. 



357 



Ml Ml U 6-K) 6-zo Ml M M 71 r-w 7-20 



Here it. must be noted that I was observing the filament in bright 

 light, at relatively high temperatures ; I attributed the slow growth 

 from 10.55 to 11.47 to these factors. 



The diagrams, which are drawn carefully to scale, give the relative 

 elongations of the cells very accurately, and the reader is referred to 

 them for details ; (he conclusion to be drawn from them is that from 

 10.40 to 10.55 the growth was entirely confined to the two right-hand 

 segments, and then it occurred in the segments to the left end. 



At 11.47 each of the right cells became divided, almost, if not 

 quite, simultaneously, so that the filament now consisted of sixteen 

 cells each from 3 to 4 /t long. 



At 1*1.47 I was taking the light almost direct from the sun, and 

 inadvertently allowed the cell to be more brilliantly illuminated than 

 usual, and the reflected solar image in fact gradually got on to the 

 culture-drop. On examining at 12.3 I found a most unexpected 

 result the whole filament had contracted from 62 fi (its length at 

 11 47) to 52 fi, and each of the 16 short cells composing it was now 

 seen to be sharply contracted and lying distinct from its neighbour, 

 from which it was separated by a broad cell wall. The whole was, 

 in fact, now a series of cells inclosed in a distinct swollen sheath. 



Still more remarkable was the fact that on again shading the 

 culture, which at once brought the temperature down from 36 to 

 26 C., these cells at once closed up again, arid the whole series once 

 more slowly lengthened out, so that at 12.18 it was again 62 p long. 

 But no more growth occurred, though more septa were formed and 

 the positions of others altered. On again turning the sun on, I saw 

 these cells once more and suddenly contract away from one another, 

 find clearly lie as contracted blocks of protoplasm in a distinct 

 sheath. 



Again they closed up, but more slowly, on shading the culture, and 

 in ten minutes all the segments were marked with fine granular 

 reticulations. 



The cells were now dead, and we may conclude that the insolated 

 protoplasm is killed by 5 10 minutes direct insolation at 35 36 C. 



From subsequent experiments at these temperatures in the dark it 

 tuny perhaps be concluded that the death here resulted from the 

 high temperature, quite apart from any possible light action, and this 



