334 



Kev. W. H. Dallinger on 



[May 2, 



tremely minute globule, also indicated at d. But as this was not 

 always present, even in the normal state of the organism, it was pro- 

 bably not important. 



The extreme length of the body was the ^ J th of an inch. It 

 rarely exceeded this and was often less. 



It swam, as I have said, with great rapidity ; and all its move- 

 ments were most graceful, varied, and controlled. Its usual mode of 

 motion is in a direct line, or in curves ; and with its trailing flagella 

 behind and its active anterior one, it is a very remarkable object. 

 But the suddenness with which it can arrest its most rapid movement, 

 or change it in any direction up, down, or directly reversed, is still 

 more remarkable. In this the flagella at the sides are brought into 

 active operation ; sometimes both being spread out like long arms ; at 

 other times one being stretched out and in vigorous action, while the 

 other is closely pressed to the other side, and so forth, giving this 

 organism a control over its movements which is of extreme interest. 

 Indeed the apparent volitional mastery which this seemingly structure- 

 less speck exercises over these equally structureless filaments, for the 

 determination of its course, cannot be seen and studied without 

 wonder. 



But besides this free-swimming movement, it was capable of the 

 most vigorous motion in an " anchored " state. Most of the larger 

 septic organisms belong to, or are associated with, certain conditions 

 of the decomposing matter ; and disappear before the advent of other 

 forms, when that condition is past. This one was associated with the 

 general breaking up of the decomposing animal matter; and the 

 movement which I am about to describe apparently contributed to 

 this. It was a powerful springing motion. The trailing flagella 

 became attached to the floor as at a, i, fig. 2, by what means could 

 never be discovered ; but the attachment was very secure and could 

 be discontinued at any moment. Directly the anchorage is made, the 

 two anchored flagella with the utmost rapidity coil in a spiral, as at 

 c, fig. 2, bringing the body of the organism nearly to a level with the 

 floor. With equal suddenness it darts up in the line indicated by the 

 arrow d, and thus having reached the limits of its flagella it moves 

 down, with equal rapidity, in an arc of a circle of which the flagella 

 are the radius ; indicated by the arrow e. In this way the whole 

 body is brought down on the point /. But the matter to be noticed 

 is, that this is never done except upon a fragment of the decomposing 

 tissues in the infusion. And if a small fragment be taken out at any 

 time and examined, it would soon be encircled by thousands of these 

 forms incessantly darting up and down upon it in the way described ; 

 and careful observation showed that they, by this means, rapidly 

 changed the form and diminished the size of the little particles so 

 attacked. No morphological changes are at all apparent in those that 



