THE PRESIDENT'S ADDRESS. 
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an inch in long diameter, high powers of this kind were necessary. 
It is very curious to know that these minute organisms aid in 
getting rid of objectionable matter. The flagella are used as 
swimming organs, but the owner has the power of fixing in some 
way or other the trailing flagella to the ground, or decom- 
posing mass, and by coiling them, " and bringing itself down upon 
the body to which it is anchored, and then suddenly darting up 
again, so as to make its flagella together the radius of a circle, it 
darts down on the decomposing substance," and by the enormous 
numbers that are thus engaged, the breaking up of the obnoxious 
tissues is accomplished. These organisms undergo fission or self- 
division, each dividing again and again. 
In September last Mr. Dallinger published his paper on the 
"Measurement of the Diameter of the Flagella of Bacterium 
termor Here it was also found " what Cohn had demonstrated, 
what Ehrenberg had suspected," and what the author and Dr. 
Drysdale had confirmed, that the movements of this species were 
produced and controlled by a pair of fine flagella, one at each end 
of its spiral body. Not only therefore in these bacteria was the 
cause of motion discovered, but there was the analogy of the 
monads, "many of them being only four or five times larger than 
the larger forms of Bacterium termo, these also being endowed 
with one or more flagella, suggesting the probability that all these 
forms depended for movement on similar mobile filaments."* 
These careful investigators then proceeded, having succeeded in 
their endeavour to demonstrate these flagella, which both, after 
separate experiments had done, to measure the diameter of the 
flagella. Now to estimate properly the difficulty of this task it 
must be recollected that the average length of the bacterium is the 
one ten-thousandth of an inch. After referring to the mode in 
which the experiments were made, and speaking of a particular 
specimen which had a diameter of one -twenty thousand four 
hundredth of an inch, the author states that fifty separate drawings 
were made, and measurements taken with each of four lenses 
tV> tV> A an d Irs objectives — and the mean results obtained from 
the whole four sets of measurements gave for the value of the 
diameter of the flagellum 0*00000488526, which expressed in 
vulgar fractions is equivalent to the two hundred and four thousand 
seven hundredth of an inch nearly, that is to say, within a wholly 
* " Transactions Royal Micro. Society" vol. i. p. 170. 
